i bought a speed demon carb 650vs for my 355 it ran great then it fouled the plugs.i put ac delco in and it ran great again for maybe 300 miles.now i am losing power and have hesitation especially at idle so i am sure my plugs are on there way out.i am afraid of making adjustments because it runs so good with new plugs.i have a 700r4 with 373s but i have 29 inch tires and i am always at low rpms (1500 at 60mph)shold i check the floats?change jets?there are so many options i am lost.any replys would help