A miss
or
A collapsed engine mount
or
A imbalance caused by a failing component, harmonic balancers and torque converters are common.
The engine is not hitting on all cylinders or the distributor (electronic or manual) needs adjustment.
could be a broken engine mount
Your power steering pump and or steering box may be about to give out on you.
Could be a broken motor mount.
Sounds like the engine mounts might be failing and no longer damping engine vibration.
The lack of oil?!?
A clogged muffler can.
Yes, when idling and driving.
My 92 PA had a similar problem. At low engine speeds it would shake pretty bad. It turned out to be the harmonic balancer. You can easily check this by looking at the front end of the engine. It is the pulley that drives all the belts. If the rubber has deteriorated, it could be the cause of your problem.
Can be engine miss or broken motor mount.
Misfire, bad spark timing, bad engine mountings.
Cylinder misfire. Possibly failed or failing engine mounts.