2001 Ford Mustang stalling and misfiring at red lights

Maintenance/Repairs
1

Hello,

I have a 2001 Ford Mustang, V6, 3.8 Liters, automatic transmission, 120,000 miles. Recently, my car has started to stall/misfire at when I come to a full stop at a red light. It feels like the car is going to shut down and like it has no power. I have to press the gas really hard to get it to pick up power and speed. It doesn’t happen every time and I’ve noticed that it happens less early in the morning or at night, and it happens more often during the day when it is really hot (I live in Az and temperatures are currently in the 100sF).
The “service engine” light is not turning on.
The battery was checked and it’s fine (recently replaced in September 2011). The alternator was changed 1 month ago. The cooling fan was replaced 1 month ago.
I took it the the Ford agency and no codes are turning up and they can’t seem to duplicate the problem even though the ran the car for 15 miles. They checked coils, spark plugs, fuel injectors, fuel filter, gas pump pressure, and it all seems fine. They advised that I fill up my gas tank with Premium gas and add fuel injector cleaning fluid. I did and the problem is still there. They then advised to fill up gas tank again with Premium and add Techrnon additive. I did and the problem is still there.

I am scared that my car will stall and turn off while doing a left turn with oncoming traffic or in the freeway.

I will be moving to Chicago in August to start graduate school and plan to take my car with me, so I really want to get this problem fixed.

Any suggestions?

Thanks,

Carolina

2

When were the spark plugs last changed? I know that the shop said they checked them, but if the plugs have not been changed, they are overdue. If they were changed, what plugs were used?

3

Could be many things but one of the first things to try is cleaning the IAC* valve. As the name implies, this device is directly related to the car idling as it would if you’re sitting still. It usually sits on top the engine somewhere so is easily removed with a couple of bolts. Shake it to get the crud out and then clean it with some carburetor cleaner.
What is the engine speed when you’re in gear and sitting still, btw?

*Idle Air Control

Edit: here’s a link that would make trying to clean the IAC a relatively simple DIY project:
http://www.muscularmustangs.com/iac.php