1996 Oldsmobile Cutlass Multiple misfires?

Olds cutlass supreme, 1996. Originally I had no heat and my car was overheating so I hired a friend to put new gasketts on the upper and lower intake this fixed the problem but now I have a new problem. The car drove fine for a day then it just suddenly died when I was driving it. I start it back up and it starts making this backfiring sound and it turns over but then it dies after a few minutes. I start it again and it gets worse with the shaking and backfiring till eventually it doesn't start. I hooked up a computer to it and it says "multiple misfires" I had a friend tell me it's a coil pack and another person told me it was the timing. Just wondering if you had any ideas before I go out and put money into fixing things that don't need to be fixed.