Mercury 60hp four stroke efi Bigfoot
by Bruce Murphy
(Winfield, Tennessee, USA)
Engine starts without hesitation. After you shift into forward, it accelerates as it should. Ater it runs at full throttle for a few minutes, the RPMs start noiceably dropping and the engine sputters until it reaches about 20% or so. If you reduce the throttle all the way, it responds until it gets back up to about 20%. It seems to run steady at low throttle;but, it you attempt to give it more throttle, it starts sputtering.
If you shift into neutral, turn off the motor and restart, it will repeat the aforementioned symptoms.