I have dual exhaust on my V6 and have had both exhaust TSBs performed on it. I was having a bad vibration at around 1500-1600 rpm when driving. With the last TSB they removed a exhaust hanger and it seems to have fixed that. But now I get a really bad vibration only when I am stopped and the engine is still cold. I mean it is really loud and I just put it in neutral so it will quit. When it warms up though it quits vibrating. Any ideas as to what this might be?

Thanks!!

 

Mind does the same thing. I have an automatic. I just let it warm up for about 30 seconds, once the rpm comes done to under 1000 then I take off. Letting your mustang warm up for 30-40 seconds is not going to hurt anything.