91 Cav. had engine catch fire

As I stated in my earlier post,my 91 Cav. was trying to stall out on acceleration,then it backfired out through the carborator. Thinking it was plugs and wires eeing as they had factory parts i changed them. After changing them she still did'nt want to stay running, then the top of the motor caught fire. I'm not thinking that it a fuel leak as earlier suggested. Does anyone have any other idea what could be wrong.