1994 Buick Roadmaster Starting Problems

I bought a 1994 buick roadmaster from a 91 year old man. I dont think nothing was ever changed. After 3 week the car just didn't wont to stay started. The engine starts but stop immediately. I was told by my neighbor that it was either the fuel pump, distibutor, ignition coil, or throttle position sensor was the problem. Not knowing where to start so I went to the auto parts, bought all items replaced what he said was wrong. I even done a major tune up. After all that work and $1100 in parts, the car still stop immediately after starting it. Any suggestion on what I should do. I dont wont to get rid of the car cause I love this buick roadmaster.