Sound problem, what could it be?

Hi,

I have a 95 Eagle Vision ESi 3.3L with 42LE Auto Tranny (I think). There's a sound that comes from under my car that is the loudest in the middle under the tranny/catalytic converter. When the car is in gear, parked, or neutral, I rev my engine and release the pedal quickly. I consequently hear a loud PSSSSSHHhhhhh noise with mild popping as if rocks are hitting metal. However, this doesn't occur if I slowly cause the engine to return to idle. In addition, this happens within the 2000-1000 RPM range.

I have a couple of assumptions but I need your opinions before taking it to a shop that might rip me off.

1. It could be the fly wheel that is not bolted on tightly which may cause such noise when it's spin suddenly changes.

2. Residue in the catalytic converted is being pushed around by heavy exhaust. Or there's just something wrong with the catalytic converter.

3. The chain in the tranny is messed up and old.

4. It could be my torque converter since when I brake the car to a stop, I feel a slight shudder in the entire car as if I just went over a cut in the road (You know those gaps that they fill up instead of fixing the entire road).

Can anyone take a guess?

I am going for the catalytic. I have had several of those over the years. I have never had a flywheel come loose. It wouldn't move anyway because it is bolted to the torque converter, and that is on the tranny splines. If it did move the starter gear would make a lot of noise. Tranny chain?? could be. I havn't seen one of those since the mid 80's. sorry I am mostly a GM guy.