[MKIII The Supra King]

Hello i just bought my 88na roughly 6 months ago, all in all an awesome freakin car i love it, little sluggish but operates normally (for the most part). Until one day i slammed it coming around a corner punched it in first then went for second after i got around, and for a split second, felt something very odd and since then i have a wicked vibration that becomes unbearable around 4000 rpm, but no misfire and no noise. it happens in neutral and in gear at any speed. i just did a bunch of overhaul after the vibration came in. replaced motor mounts trans mount, re sealed trans, rear main seals, control arm bushings, ball joints upper and lower, valve cover gaskets, plugs and wires, and im at the point where im just gonna hop in it and ride off a cliff cause i sure as hell aint sellin it. any insight would be greatly appreciated!!!!