I've got a 1978 Scout II with a 392 V8 engine that's giving me problems only after it gets to operating temperature. The engine backfires, misfires, stumbles badly, and has nearly no power after the engine gets to operating temperature. Before it's warmed up it runs perfectly and has lots of power. I've replaced the mechanical fuel pump and that didn't help. I then bypassed the mechanical fuel pump and used an electric fuel pump. That didn't help either. The fuel pressure is about 3 PSI when the engine is running no matter if the engine is cold or hot at full throttle, or idle. The timing is good at 3 degrees btoc using the #8. The carb (Edelbrock Performer 600 CFM, electric choke) was replaced before I owned the Scout, but it looks fine. The distributor and coil were replaced and didn't help. All of the fuel lines are routed away from hot-spots. Please help!!