Transmission

Immediately on leaving repair shop for Intake Manifold Gasket replacement, the car had a vibration that my body could feel slightly. That was gone the second day. I then noticed for the the first time ever, that the first and second gear shift had a thump sound, which still continues. Before taking car in for IMG repair, I do recall accidentally hitting the gear arm into Neutral from Drive as the car was moving about 5 mph. But thump shift began after IMG repair visit. What do you think is going on with the Transmission?

What kind of car is “the car”?

I’m going to guess it is a '97 Chevy Lumina.

And I’m going to guess - as a first shot - that there are one or more engine or transmission mounts that may have been undone or loosened during the gasket replacement and that someone forgot to properly torque them/it down.

It’s a 97 Lumina

Just to be clear - the hard shift occurs during driving. In the past, before IMG repair, infrequently there was a thump or clunk sound when

I’ve heard of a loose mount causing a clunk sound when the gear shift lever is moved to R or D etc, and I have experienced that in the past, before IMG repair. However,the clunk/thump I refer to in original Post occurs while driving - the car has a hard shift, more so in the first shift at 10-15mph than at the second shift at 25-30 mph, but at both. Could a loose mount cause this as well? If not, any other ideas? Transmission was serviced 20,000 miles ago.

What about me knocking the gear lever into N from D.
What about Pressure Control Solenoid