TPS or IAC?

Hi All,

Got an '87 GM that has a "slight up/down idle" when first starting. Only lasts a minute or so and then is fine. Sometimes a slight stumble from a stop. Likeliness culprit be a TPS or IAC?? Car has a little over 121K and have had it from brand new. Never remember changing the TPS but did the IAC a couple of years ago. Forgot to clean out the ports before install, though. Boy was that dumb!! Let me know your thoughts!! Thanks....MB

Use a multimeter to check the resistance of the TPS as you move it.

It could also be a fuel pressure problem.

There is an Intake Air Temperature sensor on the drivers side front that will cause the problem you describe.

Where exactly is that sensor located? Looks like it is threated into something and has an electrical connector but where is it screwed into? Thanks....MB

Not sure about on a 5.0L, but on my 4.6L it was located on the top half of the air filter box.

Yes, I had a '93 and also currently have a '95 and on the 4.6L, that is where it is. Didn't even know a 5.0 has one? Got to check the official manual as Rock Auto does list one for the 5.0.....MB

Look on the intake between 5 and 6 cylinders. it should be licated there if I remember correctly.

Hey Good Buddy! Is that Passenger or Driver's side?? MB

Drivers side. Those little sensors are suspect to carbon build up on them.