My crossfire limited just hit the 90k mark and it is extremely loud at startup/idle with a knocking sound. It has always had a little noise, but this new sound just started a little over a week ago.

My car is an automatic, while driving two or three weeks ago my girlfriend leaned over and accidentally downshifted the car from auto to 2nd gear while going 40mph. I'm not sure if that has any correlation to the noise i'm hearing now.

Any idea what the most likely problem is? I don't hear the knocking while driving, only at start-up/idle. We do not have any good dealers near me so servicing this guy is going to be a trip. I actually plan on selling the car in 4 months since i'll be moving to NYC, i'm terrified that this is going to cost a lot of $$ to fix.