It is possible the cats are bad, but with this sort of problem it's really hard to diagnose because it could be so many different things.
I had a somewhat similar problem on my 94 Cobra when i bought it. The car seemed to rev up fine but when i would get going it would just fall flat on its face after like 3000rpms. Turns out i had a spare ignition coil laying around and swapped them and that turned out to be the problem.
You should probably start with checking to see if your computer outputs any codes. Remember the engine light doesnt need to be on for there to be codes in the system, and it could help lead you in the right direction.