Subject: rough and high idle problems
Question: I have a 94 Mitsubishi 3000gt, non-turbo, with a manul transmission. The idle on the car runs high and rough on cold starts, and stays high after warm up and driving. But at times when driving the idle returns to 1000, but usually it runs on 2000 and bounces up and down around that area. When the idle runs high and the clutch is press down to change gears, the idle jumps another thousand then returns for some reasson. Someone told me that it might be my air intake sensor, but I'm not sure. So please gime me some advice that might help out. Thanks
Answer: Mookie,
Your problem is most likely a faulty Idle Air Control (IAC) motor. The IAC motor controls and regulates your idle speed when your car is in park or when you're at a stop light. It should maintains your RPMs around 800-1000 rpms. It's common for an IAC motor to fail after 10 years or so. And when the IAC goes bad, it doesn't know where to keep hold the idle speed, so it just continuously adjusts it up and down.

Call around to local auto parts stores and see if you can get a new IAC. It's easy to install and any mechanic should have an easy time to replace it.
Good luck!