idling up/down

First eliminate all vacuum or air leaks in the system. You may have a bad IAC ( idle air control) but try cleaning the throttle body first. Remove the intake snorkel, have someone hold the throttle wide open for you and scrub the back side of the throttle plate and surrounding bore with an old tooth brush and some carb cleaner. Be sure to spray some into the small holes next to the throttle plate. That should help stabilize the idle. If it still has a problem, replace the IAC.

IAC was recently, replaced within the past year... and I have cleaned the throttle body by spraying it, have not scrubbed it, but it appears to be clean when u look into it.... it looks that I may have to replace the IAC again... :(

Scrub the back side of the throttle plate and look for vacuum leaks. Also make sure it is not low on coolant.

ok, sounds good..... vacuum should not be the problem replaced all the hoses the other day, we will see what we have, after doing that... thanks for the info.

I’m having the same problem with my Nissan. I’ve changes iac,throttle position sensor, plugs ,plug wires , distributor cap. Is it possible that the gasket under the throttle body is bad? Or could I need a new throttle body?

Hello, Im Danny
You have responded to a question that is years old.You need to start a new question and include you cars information.Hope this helps and thanks for using 2CarPros.Here is the link.
Danny-

https://www.2carpros.com/questions/new

Try replacing this part, it sits in the left back corner of the throttle on the back side thishelps control the idling. I have the same problem. Nissan Part ELEMENT KIT-THERMO
Part Number: 1639112G00

Thanks. Please come back and let us know if you have any questions on your cars.