the engine is a redtop tvis standard except for pod filter,
the problem reminds me of the audi guy who put sand in his intake, the engine bucks alot and doesnt idle,
i took the pod filter off and opened the butterfly valve and quite a bit of smoke came out the intake!
then i took the plugs out and turned it over by hand, it seemed fine
then took the cam cover off and the match marks on the cam pulleys are in the right place.
before this happened it was running good.
all i can think of is that something is blocking the exhaust but i cant see any potatoes or balloons.