Engine loses power

have you checked the catylatic converter to make sure it isn't plugged?

No, I haven't checked the converter. I remember a while back a mechanic that was working on it told me I had 2 fuel injectors going out. I suppose the converter could be part of the problem too.

A bad injector or two could cause the problem. Also, keep in mind, if they are giving the engine too much gas and it isn't all being burned, that can cause the inside of the converter to melt down.

While I am driving down the road sometimes my Jimmy will lose power. I let off the gas for a second then when I push the gas again it does fine. It usually does this around 35 mph then a 2nd time at around 45 mph once i get above 45 mph it drives fine.

Any check engine light while driving? If you stand on it, does it go through the dead spots without hesitating? Please advise.

Thank You for your quick response. I took a gamble and changed the throttle position sensor and that solved the problem. Because of your quick response I will use you guys in the future if i get stumped on something.

Glad you found it. Sometimes a TPS will wear a "dead spot" in the coil where the accelerator is commonly held. They can do this and still not trip the CE light.

1989 GMC S-15 Jimmy. 4.3... Car was given to me because it was sitting in the woods. When the owner parked it, it was running rough and very rich. What i have done, ALL NEW plugs, wires, cap,rotor,map sensor,coil,temp sensor,complete exhaust from manifolds back,O2 sensor.rebuilt TBI (seals,gaskets and filters). Removed and cleaned gas tank,lines and new filter.Compression check showed a HIGH of 159 and LOW of 151.Oil pressure by gauge is very good. Still runs rich. Will start and idle, when it gets a little warm if you touch the accelerator at all it dies. Will start back up if you hold pedal to the floor and blows black smoke and runs really rough but will idle after. I am lost.. Have been out of work for a year and any help to keep me from paying a shop is GREATLY appreciated. Mike

Probable causes of an engine running rich are as follows:

1.Excessive fuel pressure can be cause by restricted fuel return line
2.Defective Oxygen Sensors.
3.Leaking injectors and fuel pressure regulator.
4.Coolant temperature sensor out of calibration.
5.Restricted air intake system.

Fuel return line is not restricted. O2 sensor is new.Fuel pressure regulator is new.(forgot to include in post) How do I calibrate the NEW temp sensor??

Just install the CTS its job is just like the choke on a carbuerator till the O2 sensor takes over the loop

What is "the CTS"

Coolant Temp Sensor?? Are you refering to the one in the intake manifold or the on in the block??

Its on top front of engine -see below