Yea so I got this issue with my 2003 ford mustang v6 manual car.

ONLY in first gear, and only happening when starting from a stop, the car will violently shake...it does do this in 2nd gear but only from a stop. Once the car is in motion the shake no longer happens, sometimes it does not occur when starting from a roll.

I can't figure it out and neither can my mechanic. We think its not a engine issue because hey, no check engine light. I thought about the possibilities of it being something with the tranny or the clutch/flywheel but if it was then it would do it in every gear no?

Any suggestions/help is appreciated, thanks.