1995 idle sensor, where iit located??

my 95 bonnie just started with a very high idle when it is first started,but alfer about 5 seconds it goes back to its regular idle, also the check engine lite would come on for about 30 seconds and go off. this just started happenin this week, it has 152000 miles and no problems since i have had it. is it the idle sensor ??and what should i check first??

Throttle Position Sensor....
Maf Sensor....
Idle Air Control Sensor....

in most likely to least likely

The idle air control (IAC) valve when going bad or carboned up will cause the idle to vary by 300-500 rpms at idle. The IAC is located on the front side of the throttle body with one wiring harness connected to it. There will be two screws holding it on, either phillips or torx T20. Remove the IAC valve and check the valve seat for buildup, you can clean it with carburator cleanner or break cleanner.

You can check the mass air flow (MAF) sensor by having the car running and tap the MAF with the handle of a screwdriver. If the idle varies or the engine stops, its the MAF.

I had an 88 Bonneville SSE that had a similar problem at startup and it was the computer. Had to have a rebuilt computer ($110) installed after an electronic technician confirmed the problem.