Check your MAF, I know when mine isn't plugged in all the way, it will go from about 1500 rpms to 300 rpms and up and down like that.

 

I dunno if that will help, but i guess it wont hurt to wait for the idle to drop and then raise it. Its just that the idle will be normal and then it will drop pretty low 400-500 and the car will shake back and forth like it has a crazy cam in it, but it will run like crap after the idle drops. I dunno well see.

 

when it drops thats your normal idle so you need to set it higher

 

if the idle is at 800 right when you start the car with a cold engine and then drops to 400 to 500 you just need to adjust the set screw for the thottle body. Open it up a little. On a cold start the initial idle should be anywhere from 1000 to 1300 then should drop down to 800 after a few minutes. Hope that helps.

 

Yea I understand the morning cold start but this happens whenever the car is sitting mainly when hot, at longer stop lights, or even in my driveway while it sits for about 2-3mins. This morning I let the car sit for awhile and like usual the idle dropped, so I adjusted the idle after this drop to where I wanted it, I then checked the TPS volts and it was at 1.05 (with car off) The crappy thing is I go to adjust the TPS volts and the TPS screws are stripped(not from me) and wont turn. So now I dunno what to do, so I just set the idle back down.

 

No put the idle at 800 the tps wont make a difference anyways

 

I had the same problem...Did a thousands things still cant figure it out...I was jumping from 900-450 then stalling out..I just lowered my timing a lil bit and raised the idle...Now it does it from 800-900 .......So if u figure it out let me no......I did eveything PVC vavle, cleaned throttle body, fuel filter, checked for any leaks, cleaned IAC, checked plugs and wires, It runs find tho when i have the spout out and the computer wasnt hooked up, i was starting to think it was a computer issue....

 

I was wondering what are the results of a bad harmonic balancer? Just curious cuz my car only runs right with the timing up pretty high, and I thought maybe it was off.

 

Those are what I like to call "Phantom" problems. They are here one day gone the next and decide to happen whenever the car feels like it. I have them on my car too. Fortunately for me they aren't as severe. Good luck with everything I hope you get it sorted out.

 

hye man you got coarbon build up in your car ask for an induction service mine did the same thing