hey guys new to this forums thing but I really need help with my 92 Mustang GT I just purchased, the car runs and drives but it isn't at full power. when it starts it idles fine but with a little pressure on the pedal right when it starts to go over 1k rpms it gets a heavy rattle and engine shake, has a MSD distributor that the old owner out on, he said he messed with the timing and also the harmonic balancer shakes crazy too. Basically stock car, stock headers and dumps (which I hope to replace) but please need help guys ! Thanks