'91 Bonneville SSE Stalling

Hey again all. Thanks very much for the help with the Keyless, but I have another problem that no one where I live can seem to fix. The car is a 1991 Bonneville SSE, with the 3800 V6. It usually runs great, but once it gets warmed up, and you give it lots of gas (accelerating) it will sometimes grab and speed up, but at other times it spuders and stalls. The battery light on the dash board also comes on when the RPM's are really high. I can always get it running again, but most times when this happens, the Service Engine Soon light comes on, and the car will quit again (sometimes). The SES light goes off as soon as you shut the car off for 10 or so seconds. It also back-fires. Another thing is that the exuast is broke in half at the back of the catylitic converter. However, the car was doing this before that happened so I can't see how they can be related, but then again, I don't know much about cars lol

Any help would be appreciated, and please ask me more questions if you need more info as I really need this problem fixed lol

Thanks everyone