I have recently finished timing my 235, as well as putting in new points, condensor, and rotor. The engine runs fine and smooth at idle. If you gradually increase the RPM the engine continues to run smoothly. However, if you "blip" the gas pedal the engine "burps"--not really a backfire type noise, more like a burp from the engine bay. When it burps the engine hesitates and almost quits. Could this be a carburator problem? What do you think? Thanks.