I would rebuild the carb it sounds like it's running lean,after it's warm does it sound like it's popping thru the exhaust as it's at idle or as you're driving?After you have it out for a drive pull the plugs out how do they look what color are they?The color of the plugs will tell you if you're carb is running lean rich and a vac.tester will tell you if you have a vac leak some where.hook the vac gauge to the wiper port good vac is 21 inches.
Pete
