HELP!! with my 75 Dart

So a couple weeks ago.. I was rearended while driving my dart. Some chick was on her phone..of course..and while i was stopped..waiting to turn..she rear ended the guy behind me doing about 45mph..causing him to run into me.. It pushed my dart a good 4 feet forward. It was quite a hit..luckily..being all steel..my dart sustained minimal body damage..the other 2 cars were totaled. However..it's running rough now. It was ruining amazing before the accident! She was fully covered insurance wise.. It covered the body damage but now I'm left trying to find a mechanic who's willing to explore the possibility that it's running rough due to the accident so i can get her fixed. So far..I've gone to one shop who proceeded to screw it up even worse and charged me 300 bucks to do nothing.. He said the needle valve in the carb was missing which is BS considering i drove the damn thing to their shop! This kid just won't man up and admit he lost it screwing with the carb.. HELP!!!