94 Grand Prix problems...

I have a 94 GP with a 3.1L engine as of late when i go to take off from a stop the car sputters, hesitates, and sometimes stalls.......also at higher temps the car won't accelerate seems like a trany problem but hoping it isn't, it seems to shift threw gears just fine before it heats up (just running at normal temp), i've been told also that i may have a clogged catalytic converter..does anyone have any advice on whats wrong with my car?

Is the "check engine/service engine soon" light on? Does it do it when the engine is cold or warmed up? How long since the car has been tuned up (plugs, wires, fuel filter, pcv)? A little more specific information would be helpful here.