My G-5 was doing the same thing,new plug wires and cleaned and adjusted the points and checked the advance with a lite, it was ok. Still had the problem. When I put the Dyna coils on I replaced the condensers with new ones also. I had the old ones hid away pretty good but I finally found them.Put them back on and the old girl ran like she was supposed.No Bog on the top end. Worked for me. Ron B