good or bad sensor?

If you have a bad engine sensor will there always be an indicator light to let you know? Or, do you have to plug in the test fuse to find out? My 93 (just rebuilt) idles high and can't seem to bring it down with the adjusting screws on the TB when the engine is warmed up. Thanks in advance, great site!!!

are you using the throttle stop screw or the one behind the rubber plug in the side of the throttle body? and you have to plug in the fuse to see if computer has stored any codes in case light came on for a bit and you never noticed it

I tryed both and still idled fast (have a Hanes manual). It also speeds up and slows down "jerky" in 1st gear.

I have not plugged in any test fuses because not sure how to do that. I hope you can give directions on that. The car had a bad engine (rings and valves) when I got it so I don't know any history on the car. I pulled the motor as soon as I got it.

Thanks Crvett69 for your help on this question and other ones!

The people I bought my car from drove it to town and back running on only one cylinder. After doing the valves, it idled too high and surged, just as yours is doing. After checking way too much stuff, I adjusted down the throttle stop screw. I guess former owner had run it up to keep it from dying on him. My surging has now stopped too, not sure why, but there is still a bit of a lurch just out of idle even tho the TPS is adjusted correctly. Another reason for fast idle is air getting around the butterfly valve (some type of vacuum leak). The ECM reads a lean mixture from the OX sensor and ups the injector pulse duration, and up goes your engine speed.