This past week, when I got to school which is about a 30min drive on the interstate, I pull into the parking spot and I notice that it was idling around 1500 rpm. I tapped the gas to see if it was just stuck and it didn't come down. I held down the brake and let up on the clutch with it in gear until it pulled the rpm's down to where they should be to see if it would stay, but as soon as I push the clutch back in, it jumps back up. I turned off the car and restarted it, and it was still idling high. I was late for class, so I left it. When I left school several hours later, it ran fine and idled fine when I got home (the same 30min drive). Well, it did the same thing today, but this time I had a few minutes so I sat there and turned it off, let it sit a minute and restarted. Each time I waited and restarted, it would idle a little lower. About 7 mins later, it was at the normal 800rpm idle.

The engine is bone stock down to the air filter. I'm not throwing any codes and never have. Any ideas? All comments and suggestions are welcomed.

98 Cobra 93K miles.

 

temperature problems?

 

Nope, everything runs fine. Wruno, I'm jealous of those rims. When I got my car, someone had put 99 cobra wheels on it, i wish i could find someone to trade them for the original 98s.

 

i have a 97 cobra with a similar issue. mine started when i had the a/c on but now it does it without the a/c. i can usually get mine to come back down to idle if i hit the gas an get the rpms up around 2500. i initially thought it was the idle air control valve. i cleaned it and put it back but it didn't fix the problem. i have talked to a couple mechs and they say the iac may need to be replaced. they said to go back with motorcraft because aftermarket doesn't work as well. i haven't bought a new one yet because it's only a minor nuisance for now. if you do replace yours pm me and let me know if that fixed it. hope you get it fixed.

 

something with the fuel probly? maybe too lean? or rich? would that throw a code?

 

Its sounds to me too like its the idle air control valve. Out a new one in and it should clear it up and if it doesnt, well you have a new one now and one thing to check off the list of possible causes.

 

I also like your rims too. I have the stock 1996 Cobra rims and Im not too big of a fan of them. I would take the 99 cobra rims over the 96.

 

thanks for the help guys. i'll look into the iac.