Idle issues plus more

[93lazerpgt]

So I have a 93 PGT that we will just say is moody. No CEL. Depending on the day it will do a hand full of different things at idle. Above idle there are no issues full power with just a slight vibration which I believe to be an issue with plug wires or the fuel filter. Anyway back to the idle problems after up to temperature it may idle at 500 or at 900 usually dropping down to the 500-600 range. Also occasionally with light pressure on the throttle I will get the surging from idle to approximately 1200. Once in a while on first start up it will only start with the throttle on the floor. Im assuming it's flooding itself out.

Now after reading all of that I'm sure you reached the same decision I did which would be the TPS is bad. I have already replaced it and tested it.

I suspect it may be a vacuum leak but wouldn't it cause the idle to stay high?

Any info or direction would be great as I have run out of ideas

Mods that may effect it:
CAI, Headers, full 2.5 exhaust including cat.

[NickR]

I think a vacuum leak can cause a fluctuating idle, not just a high idle.

This might help: https://forums.probetalk.com/showthr...p?t=1701026318

[93lazerpgt]

I have tried that at least twice. Other than testing the IAC which I amay starting to think is my issue

[J_Unit]

Check your coolant level. If it's low at all for any reason, or leaking at all, at like say the water pump gasket for example lol, your idle will surge. I did fix a surging idle once with a $25 throttle body assembly from the junk yard with a TPS and IAC on it.

As far as starting with pedal on the floor, I don't know. I have only had the happen to me after a dead disty and i flooded the car by dumping gas in it with no spark over n over. maybe you do have a massive vacuum leak somewhere, I don't know why else you would need the pedal on the floor to start it sometimes. Check front and rear PCV. if you are using the stock plastic air intake elbow with your CAI, check for cracks, especially around the back where the rear pcv hose connects.(excuse me if rear pcv is wrong terminology here, about 1/4" vacuum hose from air intake elbow to rear valve cover)

https://forums.probetalk.com/showthr...post1924192520 this thread here has idle issues and images of what i'm talking about.

[93lazerpgt]

Coolant level has been checked. If the IAC was sticking closed would that cause it to flood out? I have silicone vacuum line coming as well as the intake gasket.