96 300zx 2+2 Vibrations..

[209saint]

Hi, first posting, but ive used the forums alot for how to`s and different diagnosis ive had to make about my car in the 4 years ive had it. Its a 96 2+2 auto, all stock at 174,000 miles.

So the problem is i have a whole car shaking vibration that literaly rattles everything and the body shakes almost. It happens as i accelerate from a stop or am steady at any rpm 3000 or below, or its only a slight vibe at any rpm above 3000. Speed doesnt seem to matter, just the rpm im at. If i put the car in neutral as im driving it immediately goes away, and i can bring the rpm up and it doesnt vibrate at all, ive checked my drive shaft, center bearing is good, trans mount has been recently changed, engine mounts are good no movement or cracks. Could it be my trans going? Seems to shift harder than it use to but i cant tell for sure. Since its not the usual things ive searched for, im a bit lost at what to tackle or throw money at.