Engine Performance problem
1994 Oldsmobile LSS 6 cyl Front Wheel Drive Automatic 130000 miles

hi car pros.i have a new question for ya..i went out to start my car this morning and i noticed the engine was sounding a little diffrent..and after about 1 min of run the engine idle way down like under a grand,and the engine started bucking..so i turned it off and tryed to restart it and it did the same thing but now wont run longer than 5 sec,then cuts off..and everytime it cuts out it backfires out the intake,and my warning lights come on except the check engine and a bell sounds..what do you think this could be? i just replaced the fuel pump like a week ago,and its been running great till this morning...