I have a 90 Iroc w/350. I have an idle surge problem. It surges between 600-1500 RPMs and will eventually stall out. When I unhook the TPS it idles almost perfect...nice and steady. It will idle a little high but otherwise nice and steady at around 1100 RPMs. When I plug the TPS back in...it goes back to the idle surging again. My question is does that mean the TPS is bad and needs to be replaced? Thanks in advance.

 

You can measure the VOLT on the TPS. This need to be set to about .54V to .60V at idle.

Cheers

 

It measures at about .61V at idle. Does that mean it's still good? Also, it reads above 4.0V at WOT.

 

Also...I pulled my distributor...looks pretty rusted and worn out. Does it matter or does it need to be replaced...and could that be causing my erratic idling?

 

Adjust your TPS to be around 0.56 volt. I dont think it will help your problem. But you migth as well fix it..

Its hard to say if your distributor is the problem.
But that rust can perhaps mess up the signal to the pickup coil.

If you have ability to "scan" the car while it idle. I would be interested so teh IAC steps..

 

Also unhook your TPS makes the car go in to "open loop", and should pop up the SES ligth.
In open loop the car dont look at any sensors.
With no scan tool, you can throw money at it, replace everyting.
I can highly recommend to get a scan tool..