2011 60 hp EFI Bigfoot on a 20' pontoon. Into the shop multiple times. Replaced fuel line, impeller(not related), fuel filters, spark plugs, low pressure fuel pump, high pressure fuel pump, new screens in VST. Starts and runs perfect at low speed. Will run at WOT for a couple minutes, then starts shutting down and won't go more than around 2000 rpm. Runs longer before shutdown if at 3000. Just ordered a fuel pressure test kit but believe mechanic already checked. Problem surfaced 3 years ago. Mechanic replaced high pressure fuel pump with aftermarket pump, set off alarms. Old pump back in, everything okay last year. This year same problem back with shutdown. DIY now replaced high pressure fuel pump with OEM part. Replaced O rings on fuel cooler mounted on side of VST (leaking fuel). Lake test yesterday, same problem.