So i replaced the iac or i idle control valve i guess any ways car did fine for like 30 miles and now when i rev or run motor up while driving when i go to switch gears the rpms dont drop the stay were ever for 2-3 sec then drops to normal. What is wrong please help ever since i got my car back and trans replaced its one thing or another im fed up

 

Could it be i got a bad idle control valve its the thing on the valve body

 

I'm not sure. It may just be a mustang thing. I installed an Exedy lightweight racing flywheel which is SIGNIFICANTLY lighter than the stock flywheel and I expected my revs to drop much faster. In contrast, I noticed that the flywheel helped the engine to rev up a lot faster, but it still drops revs like a stock flywheel. I asked a few people about that and they told me that it's just the way the IAC works. But if you're noticing an even bigger delay in rev drop than you are used to, it may be something else. I wish I had more info for you. Good luck.

 

Check out the Tech articles and how to. Good basic info on your issue.

 

I have seen this several times, could be the iac is opening and allowing the idle to hang for a few seconds. someone sells the iac gasket with a smaller hole for the air to pass through. this could help.

 

Make sure the throttle stop screw is properly adjusted--here's how to do that.

Make sure you disconnect the battery for 5-7 minutes, one last time, after your final adjustment of the stop screw...

 

Ok update. So i took off the new iac and put the old back on im thinking that a got a bad iac. So only time will tell thanks for the help guys

 

Here is how to test the IAC, I had meant to post the link earilier...