1991 VW Jetta GL 1.8 liter seems to run very rough

1991 VW Jetta GL 1.8 liter mileage: 100,000. When I start my car up it seems to run very rough I have replaced a lot on the engine trying to to solve this problem; new plug wires, plugs, cap, new water pump, new power steering pump, new idle valve, new knock sensor, all new hoses and anti freeze, new vacuum lines, new air filter, new fuel filter, had the injectors cleaned at the dealer, new battery and new coolant temperature sensor. I have looked at the motor mounts and transmission mounts and they look worn, but I really don’t know if that would cause this problem but the problem gets worse when you put it in drive the car steering shakes (car not moving) and when you give it some gas the car stops shaking. It shakes at idle speed up to 10 on the tachometer but when you are stopped and you take it out of drive, it stops shaking or vibrating would be a better term. The engine runs great and does not miss at all.I have looked at the engine when put into drive and it moves about two inches or more when put into drive. Can you help me diagnose this problem?