so my idle problem happened only after driving the car hot and at idle so stopped in my own parking or stop or red light.
the rpm would go to 1000, down to 650, up to 800 down to 500, up to 500 down to 300 and die. I was able to restart the car right away. if I would press the pedal and rev it to 3000-4000 rpm the issue would go away but we all agree that we look like idiots revving at a red light
but the problem would come back at next light.
now I got to fix it but it took me I would say about 2 months of trial. I did change quiet few things but only because I wanted to it's all basic maintenance on a 22 years old 5.0 so I was ok with it since I plan on keeping the car for years.
I did all these things but none helped,
- change cap, rotor, spark plugs, spark plug wires.
- clean MAF sensor,
- clean IAC
- change EGR
- change PCV valve
- change alternator for a newer 130AMP G3
- temperature sensor for the computer and while at it temperature sensor for the dash
I did these 3 same day so the problem is I can't say for sure which one helped but at least it will give you an idea and as I said it's basic maintenance and they're cheap.
- I had a O2 sensor light on for driver side o2, I changed both sides I was running too rich
- I changed my TPS for the BBK version.
- I changed the IAC
since then so far in 2 days not once I've had bad idle being parked, stop or red light and my idle is steady at 650 RPM. I never had to play with the TB screw.
if I had to take a wild guess I would say the IAC fixed it. I didn't change it at the beginning because 2 months earlier it's the first thing I cleaned with carb cleaner but I guess it didn't help.
again this is what I did and it helped me. it's not a fix for your car, I'm just posting this to explain what I did to fix my own car.