Some 2.8L distributors came with a round rotor (Pictured below)
There have been reported problems where the screws in these round rotors will come loose and cause the rotor to destroy itself in the distributor. It will cause the engine to die and possibly result in a backfire in the exhaust.
It’s important to periodically check this when you perform your tune ups. It has been suggested that you might want to put a little Loctite on the screws to keep them from coming loose.