Rough Start aand Idle

Hi! I have a '95 Acclaim with a somewhat frustrating issue. When you first start the car it gives a big lurch and you can visibly see the steering wheel shake up and down. Then, once the car is put in gear then the entire car starts to vibrate. This is in any gear except park and neutral. The only way to stop it is to give the car a little gas. As soon as you press the accelerator even a small amount the vibration completely stops. But it resumes as soon as the accelerator is released. My dad believes it may be due to a slow idle, in part because it does not roll much when in drive without pressing the gas pedal. I was wondering if anyone out there might have any other opinion. Or if you believe it is a slow idle, could you tell me how to adjust it? Any help is greatly appreciated!

P.S. - It has just had some work done including a new timing belt, fuel filter, and motor mount. I first noticed the problem after the motor mount was installed. The fuel filter seemed to help marginally.