S10 Truck 2.2 - Virbration

1996 S10 std cab 2.2 a/c manual stock with 150K.
A vibration is progressively getting worse. I have checked all bolt on equipment, a/c, alt, water pump, ps. Removed fan clutch vibration still there. When parked and slowly increasing throttle, vibration is felt at times, however when releasing throttle vibration is felt all the way back to idle. At high rpm while on the road, can't feel vibration, however at certain speed/rpm the whole truck feels like it's going to fall apart.
Any idea?

Mel

Any engine miss or bad engine transmission mounts?

Performance is good, fuel mileage is great. Have not checked mounts.