2001 E430 barely starts

[steve dale]

Gentlemen, I own a 2001 E430 that we dearly love. It is our road car to see our grandchild and has performed flawlessly. Until, the other day when I changed the air mass meter. The Benz house indicated that the cel was from an air mass meter code. We had just received the car back from a small accident and the light came on, thus the check and change. Upon changing this part myself, the car would start after the second try and ran perfectly, then it wouldn't start at all. When we could get it to start it died and when we could get running, it ran w/ a small rev. My mechanic removed the AMM connector and the rev smoothed out, upon replacing it, it returned.
Is this just a bad AMM or something different? The AMM was purchased on EBAY from a dealer w/ a very good reputation, whom I have pruchased from before. The part number matched, but I wonder if I did something installing the AMM, it seemed easy enough, or could i have received a bad unit.
Thank you for your input.
Steve Dale