I have a Standard 1996 Escort LX 2 doors hatchback 1.9 engine. My car is raving up by itself up to 3,000 rpm sometimes when I turn it on in the mornings or when I'm at a traffic light or even ina street, I feel as if I have cruise control which I don't, then after 30 sec or a mintute it goes down by itself.

Someone told me that it was the alternator, but I checked it and is ok, is not overcharging or anything, besies I replaced it 4 years ago.

Any ideas of what's causing this?

Possibly the idle air control valve. My 93 1.9L would get stuck and stay at high rpms.

Yep... most likely the IAC... usually silver in coler and about the size of a couple of D batteries on top of the throttle body. Some people have had luck with just removing and cleaning it up. It's simple to repair on your own, just a couple screws. A new one is less that $50.