97 Cavalier idle problem

[tjn357]

Good afternoon all, first post here hope to find some answers. this problem really stumps me. Sorry for the long post, but i want to be clear on the problem and what has been done.

Problem: 1997 Cavalier 2.2 liter having problems with a high idle, car also surges at idle. (RPMs go up and down.) This problem is only happening at idle, once I reach a cruising speed on the road car seems to run great. problem does not seem to happen until motor is at operating temp however.

Now a little history: This problem started after I changed the timing chain and had the head rebuilt. (Bent all valves when timing belt went bad.) I checked fuel pressure at the pump and all is good according to the manual so i even did a running pressure test for the fuel system. This also is good according to the manual. I did replace the fuel filter, (needed to be done anyway) I also replaced the fuel pump because the readings on the electrical side of things did not seem to jive. I replaced the plug wires when i had the top of the motor torn apart waiting to get the head back. I have also replaced the thermostat, (another that needed to be done and while the car was apart easy enough.) replaced the cap on the coolant tank as well. (This was leaking and not holding pressure.)

i have tested all the sensors according to the test procedures in the manual and all seem to check out fine. The only thing i can find on the code scanner is a code for idle speed higher than expected.

Any help or ideas would be greatly apprecieated. Thanks for the time.