low idle

It sounds like you have 2 problems going on here. First the Idle Air Control Valve , IACV, has failed or needs cleaning. It is located on the intake manifold near the throttle body. Second, when you install a new battery sometimes it takes a little coercing to get things to isle correctly. This walk through will explain. Just folow link below to get to it;

https://www.2carpros.com/articles/engine-stalls-idles-too-high-low-after-dead-or-replaced-battery

If you decide to clean the IACV then make sure to use brake cleaner and spray inwards towards the intake tract and clean the ports on the intake manifold as wel in the same fashion. This keeps deposits from being pushed closer to the IACV.

I have an 06 Gt Mustang and every time the air is turned on the car idles low and speeds back up. Also when coming to a stop the car almost stalls out but then picks back up. Of course ford says thats normal, but i know better any suggestions or tips?

well, that's not normal because mine doesn't do anything at all when i turn the air on or come to a stop. sounds like the TPS throttle position sensor might be slow reacting and may need to be changed out. should be under warranty. if one dealership is un-willing to fix it. go to another dealership.

This guide can help fix it

https://www.2carpros.com/articles/stall-at-idle

Please run down this guide and report back.

Recently had it worked on and after he put it back together the idle is low and seems to bounce and pulse. it now has a flutter sound. It did not do this before he took it apart.

Take it back to him so he can see if he left something disconnected he should fix it for free depending on what was done.

I did, he said it was the mass airflow system and I should get rid of it. Thank you. I will just take it to the dealership.

sounds like the guy does not know to much or what to do he is probably talking about mass air flow sensor. make sure ductwork going from engine to air cleaner is on correctly and has no holes in it.

The car is a 2005 Mustang GT, 4.6L 3V automatic. The car is factory stock no mods.
I had to change the battery, The old battery was developing a shorted cell. After changing the battery over 3 weeks ago, I now have a problem with surging idle. It hunts up and down between 400 and 750 RPMS. It is amplified with the AC on. It sets a DTC p0506 "Idle RPM lower than expected" I can't find any vacuum leaks or air leaks. I followed a learn procedure, but mine must be really dumb. It hasn't learned anything yet.The air filter is stock and new. I replaced the TPS..no difference. There is no idle air control valve.

The IAC is now called the electronic throttle control motor, and you do have one...on the throttle body!

i had the same problem i also have auto. FIRST remove the positive red battery terminal to start work. i removed entire CAI also TB, cleaned everything with carb/tb cleaner that you can get at ford also known as tune up cleaner. 2 sensors replaced throttle position sensor on the left of TB and the MAF. if you can't afford use electronic cleaner or non residue cleaner or MAF sensor cleaner and clean all sensors. also spray the connectors with electronic cleaner. the TB had black gunk behind the butterflies. also if the air cleaner is old replace or clean. i had the steeda cone filter. i cleaned it with k&n filter cleaner. i let it sit overnight everything to dry. the next day i did not over spray the filter with the special oil provide by k&n. i but the whole system back making sure all bolts tight and no air leaks out. FINALLY, return battery terminal back. with my diablosport tuner returned the original tune back to car waited a few minutes then returned the steeda/performane tune back to my mustang. cycled the key then started. WOW
the car runs like brand new no idle surges no low idle p0506 no intermitant mass air volume blah blah
p0104. no check engine light the car is faster. Do this if you don't have any other problems with your car and the only codes are the above mentioned. After a few years the system gets dirty needs cleaning don't let dealer tell you that you need custom tune don't trust them to clean the system do it yourself, you only know how good is.

May be a cleaning, but if you remove battery terminals to protect against accidental grounding, it's the (-) negative you remove...

Been meaning to get back to you guys with a responce. At first, I didn't think the information would be useful. After cleaning the MAF and replacing the the TPS I still had idle problems. I also had a throttle lag. Push the pedal gently...nothing...then all of a sudden the RPMS would jump up. It was also nearly impossible to hold a set RPM in neutral.
After reading the mechanics reponse, I bit the bullet and purchased a replacement throttle body which comes complete with the TPS and Throttle motor from Ford Discount Parts. It is now running as good as new. I think the throttle motor may have been bad. Thank you all! It is once again a pleasure to drive it.

Don

This guide will help fix it was well

https://www.2carpros.com/articles/throttle-actuator-service

I have a problem with my Mustang, it will not idle without me pumping the gas?

Is the check engine light coming on at all?

i will be general since you provided no motor size.

idle control motor is a common failure.

is the check engine light on??

Roy

I have a 2000 ford mustang. When I push the clutch in to shift the RMPs don't drop to an idle impeding me of shifting without a grinding noise. I have to wait til my car's RMPs drop below 2000 to shift the the next gear. I don't know what is doing this, i just started when I turned off my car and turned it back on after 5 minutes. The car idles and revs just fine with the clutch in and in neutral.

Sound like the clutch is slipping preventing from you to shifting to the next gear

does that mean the clutch is going out?

Could be have it further checked

My car was running just fine before i added some headers on it. Now it wont stay on unless i keep my foot on gas pedal. After running it for about 10min. it'll barely stay on with a low idle of 300 rpm, then it just sounds like its accelerating and unaccelerating. If i rub the engine too high it turns off. My buddy says its because the computer memory of the car is not used to the new part, is that true? Or is it because i need to replace the idle control? or clean out the throddle control? Can you help me?

On some cars the computer needs the backpressure from the stock exhuast system in order to properly calibrate engine parameters. I've seen cold air intakes that don't use certain restrictions or baffles that are set into stock models turn on the check engine light and make the vehicle behave irratically. Your friend might be right. Were you able to place the oxygen sensors?

No not yet, but regardless im gonna switch the idle to see what results may i have from that. And i will also try to place the oxygen sensors.