Usually after I finish working on my car it is in better condition than before I started. But not this time.

I had a small stumble at idle that has been nagging for a while. After using the stethescope method and the water spraying method, I haven't been able to find any vacuum leaks. So, one day while I was at a PNP I found a 007 AMM in good condition that would work on my car. If I swap out my old one, it might solve the stumble, and if it doesn't I have a spare for when my current one dies.

Yesterday, a couple of months after picking up the new AMM, I swapped it into my car. After I swapped in the 'new' one, my car would start normally but then die immediately. After a few failed start attempts I unplugged the AMM and tried starting again. Started up fine. So, sounds like the new AMM is dead, right?

But, then I swapped back in my old one. And the car had the some problem, start right up and then die. Again, limp home mode works fine.

I should also note that before installing the new AMM I checked the resistance values of the new AMM that Bently mentions and compared them to my old one. Everything looked good.

So, I want to say that I fried the ECU but limp home mode still works. Is it possible that I fried it in a way that only shows up when it detects an AMM? I am going to go through Bently for tests to run on the ECU but does anyone here have any they can suggest?

The one thing that I screwed up on while I was working is that I noticed that the ignition was in position 2 when I unplugged or plugged in the new ECU. I think I did this before I noticed the problem but I am not sure. This is supposed to possibly fry the ECU, but would the ECU still work in Limp Home Mode even if it is fried?

You should also know, I checked all fuses, and I looked around the whole vicinity of the AMM for any hoses that I might have knocked off by accident but all the hoses look good. None of the hoses have cracks in them, some are new, like the bellowed one.

What do you guys think the problem is?