Hi-

In the last month, my car has been throwing the occasional "Check engine" light, but it only stayed on for a few seconds, at most. I though it was related to the air conditioning, since it usually came on right after I turned on the AC.

But tonight, on the drive home, engine surged quite a few times, and stalled three times. I had to keep the RPMs pretty high to prevent it from stalling out. I also noted that the idle, when left to its own, was higher than normal - my car usually idles at almost exactly 1000 rpm, and it was closer to 1500. My guess is that it is the AMS.

I unplugged the AMS to put it in "limp home mode", and while the idle is rough, it seems better (aka less stall-y).

Questions:

1) If I want to confirm that it is a bad AMS, what do I do? How do I "read" codes to figure out why the "check engine" light illuminated? Do I need a special tool?

2) What happens if I put my spare AMS, which is the wrong one, as a temporary fix? The part number on my car is 0 280 212 016. My spare is a 0 280 212 007.

3) Is it better to run it in "limp home" mode or with the wrong part?

4) Aside from terrible MPG, what happens if I run it in the better of "limp home mode" or "wrong part mode" for a few days until FCP ships me the replacement part?

5) OEM Bosch costs $319. GULP. There is a rebuilt AMS from "Injection Labs" for $159. Is the Bosch better and worth the additional money?

6) Anything else that I shoudl replace at the same time?

Thanks for the advice!