1992 Hesitation when cold

[rw1966]

I have a 1992 GMC Sierra 350 Throttle body injection, 166,000 miles

When the Engine is cold it runs great! after warm up the truck has
a bad hesitation and chokes down when driving slow , like in a parking lot
or pulling away from a stop light, If you give it gas it picks up and goes on.

It runs great other than that

I have changed the plugs , took the throttle body apart cleaned and put back, changed fuel filter

Any suggestions to look at ??

Thanks

[2000CAYukon]

Sounds like the engine coolant temp sensor could be bad. There is also a heat riser coming off the passenger exhaust manifold. They go bad and only allow hot air to enter the intake. Either one could cause it run good cold but bad hot.

Using an ohm meter, read the resistance across the engine coolant temp sensor (intake manifold near the tstat) with the engine cold. Then get a reading with it is warm and post the results.

The valve for the heat riser is in the air cleaner so you need to take it off and look at the valve. When the engine is warm, it should close allowing cool air to enter the intake.

//2000CAYukon

[rw1966]

THANK YOU That was it ,
I Really did not understand how to read ohms across the sensor, so I unplugged it , runs great now.
Drove a while with it off and put it back on and the hesitation started back.
Unplugged it again and it ran fine.
Autozone has a replacement for 11 buck , I'll get one next week on put it on.

Again thank you a lot , I was about ready to head to the shop $$$$$