i have a 91 4wd pickup with the v6 3.0 engine in it. I'm having some trouble with the idling. It idles, but the idling is real rough, going up and down, almost like i'm just barely reving the engine. A mechanic is saying that its the "idle sensor" but i don't know how trustworthy he is. My check engine light is on. I know that you can put a wire into the obd1 plug and then the light blinks to tell you the code, but i don't know how to jump it. Could anyone here tell me how to do it? and any speculation on the idling would be nice too.

 

Also, i don't know what this means, but today i changed my brakes and pcv valve. Once i finished and started it up the engine was idling as it should. it sometimes does this when i first start my truck so i revved the engine, which normally makes it go back to the varying idle. It stayed running fine no matter how much i revved the engine. then after a couple minutes i went to adjust the idle, because it was a little high, but before i touched anything i revved it one last time and it went back to the rough and varying idle.