engine vibration

I have 1992 Galant 2.0 mpi. Lately the the front end of the car vibrates excessively when in low gear and when a/c is on. Also shift shock is happening occassionally.

What sould be the problem of my engine/transmission?

 

[SouthCaliVR4]

I would start by checking the condition of the timing belt, particularly the smaller balance shaft belt.

are we talking about a vr4 or a regular galant? if it's reg, single or twin cam? on the twin check the spark plug boots for arcing in the plug wells. other wise we need more information.

Can you clarify the phrase "Shift shock" auto or manual trans?