Got the car back after a year, it was broke down in a parking lot. I did manage to drive it home. (It worked fine a year ago)

Any way, when I got it back it wouldn't idle, woudn't go, shut itself off, mis firing, Broken ERG valve, whole lotta noise, overheating, clogged fuel filter, clogged Catalytic converter just a big mess. Basically have just been dealing with one little issue at a time, to fix.
I replaced ERG valve, fuel filter, serpentine belt, water belt, spark plugs/boots, Mechanic hallowed out the catalytic converter, oil change, and new battery.

After all this I can drive it (woo hooo!!!), however it hesitates to go, but will go. is fine while driving. But has decided to just not go and float 20 feet, before driving. starts to shake/jump when flooring it, or reving above 4 rpms.
So I guess I would like your input on what would cause the car to not go above 4 rpms, but instead jump and shake at 4 rpms. That would also cause it to hesitate to drive, to that would it not go and coast for 15-20 ft, before kicking on.
Am I looking at yet one more problem, or a collection of problems still?