I have a 1999 Chev. Cavalier Z24 with 2.4 twin cam. My problem is that since it has become cold when I first start up the car the engine revs very high until the car warms. Also the check engine light came on the same day?

Attach a code reader to the under dash data link connector and check for codes. Some auto parts stores will do this for free. After you fix the indicated problem, use the code reader to erase the code. Then, the CEL will go out.