I'll be driving along at a steady pace and I'll hear a pop. Any idea what's going on?

Running a 3.0 with PMOs

Sound from where? Tail pipe or burping back thru a carb?

Carbs. Might be a backfire. Not very loud.

Take the filters off and see if you can get one of the venturi to sneeze. Does it happen at the same rpm consistently?

I'll need to check. What do you mean "sneeze"?

Usually you start looking if the timing is too advanced or the engine is running lean. However, that will usually cause a fairly constant backfire through the carb, not just an occasional one.

Pull the idle jets and soak them in carb cleaner.