99 escort se 2.0 5-speed 140k sometime the idle will run up to around 2500 rps and hold some times it hangs around 12-1500 rpm and some times its normal. Can't see a pattern and I never know when its going to do it. I suspect an IAC motor but it is not throwing any codes. Looking for ideas or suggestions.

 

You may not be seeing any codes because,
The computer thinks it is sending the message to the IAC and the IAC is supposedly responding, but mechanically it is not . The IAC possibly is sticking and the idle is erratic. Replacing it usually gets rid of the problem.