89 305 TPI 5 speed. I'll start the car cold, it will idle fast as usual. I could drive 50 miles, car is nice and hot, but until I stop, the idle will not come down. After I stop at a light or stop sign, the idle will imediately come down as usual and everything will be fine for the rest of the drive. If I don't come to a complete stop, it will idle high around 1300 when I'm off the gas and in Neutral. If this isn't normal, I don't know where to begin to diagnose the problem. Thanks for the help guys!

 

my car does the same thing most of the time..i dunno whats up!!

 

check your iac. and clean it.

 

IAC huh. Damn, I've cleaned my throttle body to no end and also cleaned the IAC. I have a bit of a rough idle as well. I'm wondering if I should just take the plunge and replace the damn IAC. The car turns over a lot before it starts as well. Runs like a dream though once it gets going.

 

Is the idle eratic, or is it constant? Constant idle at 1300, reset your IAC. Eratic idle could possibly be an ECM problem. At least, it was when I had a similar problem. Idle would go up to 2000, sit for 10-20 seconds, come down to nearly stall, go up to 1000. Basically, all over the place.

 

Hmm. Actually, it sometimes will go up to about 2000 after starting, imediately drop down (not really to a stall) and then it will go back up to 1300. Once it is idleing it is pretty steady but a little erratic. The motor is fresh and runs like a top otherwise.

 

Once its warm, it will come down to a normal idle.... It does not stay at 1300. I did reset the IAC as well as the TPS to no avail. I don't mind changing parts but if I don't have to I don't want to.

 

The TPS sensor and the IAC stepper are actually fairly cheap. About $60.00 for both.

However the erratic idle can be the result of a failing ECM. It was in my car.

Before my erratic idle issues ended I had to change my TPS, IAC, MAF, ECM, Clean the TB, replace most of the hoses in the car. It wasn't pretty.

There is a thread called Fluttery RPMS on my last NERVE!!!! Search for that and you will find a huge amount of information on the subject.