I had an issue with my car stalling at a stop sign. after some reading I did some adjustment on the dashpot. now the car wont stall, but on occasion the engine wants to rev up and down by itself and when driving the car keeps cruising by itself even if I don't touch the gas pedal. I made sure the throttle plates are fully closed when I led off the gas pedal. from the looks of it a dashpot is just a device to cushion down the throttle plate when you take off the foot off the gas pedal right?

 

Correct, the dashpot is basically a throttle return damper that allows the throttle to close slowly for the last few degrees of movement. It prevents it from snapping shut and possibly getting stuck and causing premature wear on it's components. (edit) It can also keep the car from stalling if you let off the pedal quickly. You may have adjusted it out a little too far; that's the first thing that happened after I adjusted the one on my car.

 

IIRC the FSM has instructions for testing and setting the dashpots.

I'm assuming this is a manual tranny. If it was a conversion or swap you might want to verify that the neutral and clutch switch signals are getting to the ECU. If they arent, the car will tend to die at stop signs. The ECU uses those signals to temper the engine decel.

 

I deleted the dashpot (and secondary throttle plates as well) years ago with no noticeable ill effects.
I think those two devices are more emissions focused rather than drive related.

I'd pull the throttle body and confirm the whole fast idle (thermowax) mechanism is set up and working properly. Just back the damper adjustment off, so it's completely out of the picture.
With the throttle body in hand (or on the bench, more likely) and the manual handy, the system actually makes sense and is easily tested by running hot/cold water through the thermowax and seeing how the linkage reacts.
After you're satisfied the throttle body is acting right, warm up the car, ground the initial set coupler and adjust the TPS.

The "cruising by itself" detail is why I think you might have a linkage/mechanical/cable problem.

 

Sounds about where i was once. Car would stall, the reving up n down only when cold(think thats the thermowax in my case) but i noticed 2nd gear would drive faster than normal when cruising thru a plot. Maybe you went a tad far on ur dashopt adjustment. Hard to fix to factory specs with one person if i remember correctly so try a couple different positions. Also check behind your clutch theres a little plastic stopper piece that breaks and doesnt allow the plunger on the clutch switch to press in. Thats probably not ur problem if your not stalling anymore but figured you could check it anyway.

 

alright, its a gxl with a t2 swap. no thermowax hooked up. and uses a gm iac .
I will play with the dashpot.
vrracing, I am not really sure if the signal from the clutch is fed through the ecu. it has ps1000.

 

Ah, I dont know what provisions the PS1000 has for controlling off-throttle decel. Seems unlikely the stock ECU would control it but the advanced standalone would rely soley on dashpots.

Good luck!