My 1995 Buick Riviera

Please, please please can someone help me. I have a 1995 midnight blue Riviera that I love dearly. It has just turned over 52,000 miles and when it is running it rules. I have the 3800 engine package with the supecharger (man that thing makes it fast). Anyway, here lies my problem. About a month ago, the fuel pump died. I replaced it and all seemed well for about a week. Then for no apparent reason, the car would start and run for 2 to 5 seconds then die. I checked all the wiring and vacuum hoses to make sure i didn?t knock anything loose yet all seemed well. Still, the car starts, runs for 2 to 5 seconds and dies. I am thinking one of the sensors has given up the ghost but I wanted to ask you expert people your opinions first. Which sensor would you all expect? I?m in dire need here so any help you can give me would earn my eternal gratitude. Thank you sooooooooooooo much......WesG