Sudden Power Loss in 1973 Mercury 20 H.P.

Recently had problems w/ loss of power. Dealer said the carb needed to be re-built. $280 later, had boat on lake running at full throttle--ran perfectly, 14' alum boat on full plane----for about 2 minutes then, like throwing a switch, engine lost power, ran rough, but did not die, but ran o.k. at idle/trolling speed but would not increase power when throttle was increased. So after trolling for 3 hours, headed for the ramp and opened the throttle and engine worked perfectly at full speed. Then yesterday, 2nd time on water since carb re-build, engine again worked good at full throttle and at idle, suddenly coughed and ran rough then cleared up and worked perfectly again at full throttle. Could this be something as simple as trash in the fuel line somewhere? Or bad filters??

Re: Sudden Power Loss in 1973 Mercury 20 H.P.

Could be. check for bad wires. For 280 bucks,I would take it back to the dealer.