Automotive → 1994 olds 88 royal

i have a 94 olds 88 with a 3.8 motor that is giving me fits trying to figure out. it will start and run about 2 seconds before stalling. this goes on from 5 tries to 20 or more than it will start and run . after it warms for a bit you can drive it but runs rough and stalls out. the strange thing is after it stalls when starting or driving and you try to start it right back up it just turns over like no spark or gas ,but if you turn the key to off than try to start it starts back up. i have changed the plugs ,wires ,crank sensor and the egr valve and gasket. someone told me the computer is bad and im tired of hit and miss part changes.
any thoughts or suggestions to help

ok it was the computer but thanks anyways