Engine stopped after running for about an hour, anchored and watched the sunset. Wouldn't start-got home on trolling motor. Removed carb, cleaned/inspected thoroughly, checked fuel lines and bulb for flow, cleaned inline filter; made sure float adjusted properly, still wouldn't start. Finally replaced fuel pump (two stage) diaphragm and gasket with new - old one was shot, stiff, losing rubber (Note to self: replace diaphragm at less than 20 year intervals!) Absolutely no hesitation when started up! Boom! like new. Idled like a champ - no problem! Out on the lake gave it WOT and ran like a scalded cat for . . . . .about 40 sec's . . . . .lost power as if running out of fuel, so backed off throttle (didn't die) and idled for about 5 min, then WOT again (bat outta hell!) - then same thing . . . motor idles along at low speed (1200 rpm) just fine . . . .will run at 2000 rpm for about 4 min is all w/o dying .. . . . haven't checked compression . . at a loss . . .definitely unrestricted fuel to pump and to carb - all vents and jets/orifices clear . .