I just purchased a 1985 Evinrude 25 HP. It starts up very easily, but will not idle. I have to almost "feather" the throttle to keep it running. I can slowly increase throttle to about 1/2 and it runs great. However, any sudden Wide Open Throttles, and it cuts out, then revs, then cuts out, then revs. If I pump the fuel ball about every 3 seconds or so while throttling, it runs great. Any suggestions? Fuel pump? Carb rebuild? Engine model number is E25RC0S I have been running a 50:1 fuel mixture.<br /><br />Thanks, Duke