I've changed out the MAF and the Idle control sensor because I was having a weak idle and couldn't find any vaccum leaks with a smoker. I believe the engine code I got was P1707 (or whatever code tells you it's the MAF). After changing those out, my TPS (which I replaced as well) started to punch intermittently. It would constantly fluctuate. After starting it, I'd have to put it into gear immediately or it would go up to an idle of 3,000+ RPMs. When I shut the engine off, it would shake violently. We tested it and found that the TPS was wonky while plugged in, but gave perfect readings when the car was off.

I tried unplugging it and letting it set, with the ECM unplugged and the negative battery cable off... thinking that might 'reset' it, but that obviously didn't work. I couldn't figure out what was going on because there were no codes firing off... until just recently. I got hit with a P1870 (because 187 doesn't sound grim), saying there was transmission slipping... which there was now, between 1st and 2nd... but when the code popped up, the TPS seemed to chill out. I'm not saying it's all well and good, but I can have it in park without it rev'ing to 3000 now.

Finally, the P1870 code just erased itself. Poof. Gone. 1st still feels like it's slipping, but I don't know. I have no clue. Any sage wisdom would be much appreciated.

 

You need to rule out a vacuum leak or a source of unmetered air:

1. What are your 4 fuel trim numbers at idle and again at 2500 rpm?
2. Check the air horn after the MAF
3. Try blocking the brake boost hose
4. Have you done in LIM gaskets yet?
5. Look at your TPS output at key on back and forth through the full range
6. Check your TPS reference voltage and signal ground
7. We may need to check the TPS signal wire back to the engine computer if the above shows nothing

George