son has this motor and when we went out saturday it ran good for a few miles and then started to act like a fouled plug,bogging and kicking in and out of full throttle.ran back to ramp at full throttle but no rpm's,ran smooth like it was hitting on all 3 cylinders but could not get any speed or rpm's.changed plugs and still could not get any rpm at full throttle!we've had a lot of extreame air temp changes here(30 for a couple of days and 60 for a couple,roller coaster weather) could this be water in the carbs caused by condensation of the ethenol gas in the tank??that's my guess!or could it be the power pack and how do you test that? any suggestions or quick fixes would be greatly appreciated.