Huge vibrations when stopped

Need some help...........
I have a 1995 Jeep Wrangler Rio Grande, it started to get a slight vibration a few months ago when the jeep was stopped at a light but went away as soon as I hit the gas . Took it in for a tuneup and the problem went away. Cut to a couple of days ago and the problem came back worse then ever. Dropped it of at the shop, they replaced the motormounts (the mounts were falling apart and the engine was riding down low a few inches) . That took care of the the vibration sound (converter bouncing off skid plate) but the vibrations are still there. What the heck do you guys think it can be?

follow your exhaust pipe. Is it anywhere near any cross-members or anything? That will cause your problem

Thanks for the advice...........
I had the shop take a look at the new mounts that they installed and they noticed that the mounts had no give at all to them so they were transfering the vibrations from the motor to the body instead of damping them. We'll see, the new (new) mounts came this afternoon and they are going to take another shot at it in the morning. This is like when my computer went screwball and kept taking around 20 cranks to start. It took the dealership two weeks and the chief wrench head taking the car home with him and having it die out in queens before they finally figured out the problem was not the fuel lines but the computer. Thanks again