My car has this problem. When I start it up, it idles really high, like my foot is on the gas. Once it warms up, the CEL comes on, the high idle stops, and the temp gauge drops to nothing. The CEL will not turn off and when it is on, the engine runs in a rythmn like rev up and then down, up and then down and when it is doing this it is very hard to accelerate smoothly. Any ideas on how to fix this?