Hi, I have a 1988 Firebird Formula 350 TPI that I seem to have a little bit of an issue with. Over the course of about a month I have noticed my Throttle Position sensor's voltage will go up from where I have set it previously. Pretty much every time I've taken it and set it at .55v, it would run pretty decent minus every once in a while dipping low in idle (about 500 rpms) for a short amount of time and taking itself back up to 650-700rpms. After about a week or two, I notice the idle starts to get high, or rough, and when I pop the hood and recheck the TPS, it will be around .745-.75v. I am making sure when i tighten it down that the voltage doesnt go up, so its not that. Any idea's? I wouldn't think the sensor itself is faulty because I don't really have driveability issues other than that occasional idle drop. Could it be the throttle body, maybe sticking or something?

 

could be throttle blades sticking. feel inside the throttle body and see if its gunky. mine was full of sticky black carbon.

 

Yeah, thats a good thing to check. Make sure the blades and housing are clean.
While your in there cleaning up, get some electrical parts cleaner and clean your maf wire esp if your running a K&N..
My 89 has always idled around 550-650..

Wow my 3,000th post...