I like where your head is at with this. Usually when the motor mounts shart the bed, its very apparent. O
P.- want to test this theory? Just firmly grab the valve cover and give the engine a few good rocks. Worn mounts will allow the engine to move a few inches fore and aft with no problems. If you find it worn, spend the time and money and replace all of the mounts(3), its worth it. The turbo cars go through them easily. Advance auto used to sell an upper mount that was filled with polyurethane to all but eliminate breakage and not transfer vibration into the cab of the vehicle.

Pull plugs, check condition and the gap- if its a factory replacement engine, make sure your plugs are gapped properly.
While the vehicle is idling, spray a mist of water over the plug wires. Look for sparking. The oem coils on these are good units, the plug wire are known to degrade due to excessive heat from the turbski.
Make sure the throttle body is spotless and free of oil.

Let us know please