Bogging down

Hi all have Gen 4 Crusader 7.4 engine starts fine idles up to 3000 RPM okay after that the text are the tachometer starts going back and forth and then it goes right back down and shuts off can wait a while then restart the engine try to time the engine it only had 50 degrees + 1100 RPMs if it goes down to 700 RPMs the thing runs extremely rough replaced the fuel pumps I've replaced and rebuilt the carburetor I've checked all of the wires for the spark plugs spark plugs are fine I'm thinking distributor or timing Advance what do you think when I take it out I run up the engine to 3000 RPM that seems to be fine it'll hold at 3000 RPMs which is right before playing and then the tachometer starts going back and forth in the engine start sounding rough and then it gradually drops off and like I said before it most of the time will quit I wait 5 minutes then gym will start up again but then run run roughly for a while and then quit again I'm thinking this is a timing issue or something's wrong with my distributor or maybe I don't have the distributor in the right position for when the pistons pistons at the top of its cycle what do you think

You mentioned plug wires look ok - what about the Plugs? same for CAP & ROTOR??

Is this an original points distributor or has it been converted to a breakerless system? If the former, the points and condensor should be checked/replaced. In either event, if the advance isn't functioning properly, it could contribute to the symptoms described.