1994 mercury 150 hp xri fuel injection slowly loses power while driving boat at wide open throttle. Gets down to barely 5 mph and wont respond to throttle up. Shut motor off for about 5 seconds and she can get back up on plane for a little while and then loses power again. Shut off engine. Start it again to try and get up on plane...sometimes have to shut it down and start it again multiple times to get her back up on plane. I'm thinking a fuel delivery problem