My car idles weird. I have a 1991 Toyota Mr2 (non turbo), and when i start her in the morning, when its cold out, i wait for the engine to heat up a bit and then i take off. When i first turn the engine on, it runs at about 2000 RPM, and slowly comes down as it heats up. But lately, it hasn't been coming down past 1500 RPM. The engine will have been running alot, i'll be at a red light, and it'll be idling at 1500 and even 2000 RPM. It rarely comes down below 1100.

I can't understand it. Isn't there a chip that moderates that? Could that be messed up?