Need help with idle and rpm problems. Car hardly able to be driven
Before I get started, I'm not some car genious so I will attempt to list as much significant detail as possible. I have an 01 GT that has been driving perfectly fine. Well I dropped it off at an auto body shop to get some touch ups done (I live in a small town so it was some huge body shop, just a man working out of a shop garage). Well when I picked it up I heard a little clank noise and it sounded like one of the combs in my catalytic converter (as stated by a couple people) so I went on with myself. (Not sure if needless info but I want to be sure to cover everything thats gone on between now and then). I got my car back 2 days ago. Today after running some errands, on my last stop, I started the car and the rpms dropped into the 200s and fluxed between 200 - 500. This was all of a sudden, and it was perfectly fine when I pulled up to the place I was at. After a couple seconds the idle became a little stable stopping around 400, which is not normal at all for my car. I attempted to drive it a ways, and every time I would mash the clutch to shift the rpm would easily go from 2k+ to 100-200. Also when driving, it seemed like I had less pickup (was not giving it much gas so I couldn't really compare to the normal, but it did seem to not want to go as much). The sound of it seemed to be different too, normally it would be fairly loud at 1.9k rmp, well the normal sound now seem to sit around 1.6k - 1.7k rpm.
Overall 1. Very low idle
2. Sudden drops in idle when shifting or in neutral and given a rev
3. Less go
Any help would be so much appreciated