I have a 90 mustang gt that im reabuilding having a big problem though the tranny/engine shaking really rough on a hard launch. ive stripped down the engine and built it back up the engine runs great however if I launch really hard I get a ton of vibration at around 3000rpms that make the whole car shake if I slowly work my way up to top rpms though I get very little to almost no shake as far as I can tell weve fixed everything on the engine and we checked the motor mounts took them out they appear to be perfectly intact, tranny mount looks good and all the bolts for engine and tranny have been tightened down. not sure what im missing but I cant figure out whats making it shake so hard. any advice would be great