1994 Mustang Convertable

[HISSIN50]

im with CP on that one. the balancer is on the crank. we are both assuming this occurs while idling (not moving). take a look at it. there is an elastomer (rubber O-ring) in the middle that locates the two halves. if the rubber looks cracked at ALL, or you look at the thing and it is wobbling, get a new one. or if you time the car, and the timing marks are a ways off, that suggests that it has slipped.
please dont drive your car like that. the balancer quenches torsional vibrations - the bottom end does not like to be run with one out of phase.

a lot of folks are very happy with Romacs (SFI), but they are pricey. if you dont rev real high often, something like a Pioneer non SFI should be sufficient. also, LRS sells a PP non SFI unit good for 6.5K (rpm) for 80 bucks, and it is reportedly a good piece.

good luck.