I have a blue strip merc. 20 hp. Serial#3234110. It runs fine at idle till about 3/4 throttle but at WOT it just dies. Rebuilt the carb and fuel pump,pressure tested the fuel line all checks Ok.Also changed the points and top crank seal 5 years ago. If I pump the primer bulb it will run WOT. If I idle for a bit then go to WOT it will run WOT for about 10 seconds before it dies.It always restarts. Any suggestions would be appreciated. Thanks in advance.