i got a '97 bravada, at random times it will take a very long time to start and will eventually start but immediately shuts off once i shift it into reverse or drive. once in a while it will shut off while im driving but turns right back on. its weird because my rpm's just drop but then go right back up to where they were. what seems ironic is that almost everytime it shuts off the air bag light blinks. i would say it is something to do with the electrical or fuel system, but what do i know.

 

Is your CEL on? Sounds like a bad ISC motor.