I have a 7.4 efi mpi that we rebuilt and after the rebuild surges , when i put the boat in the water for the first 10 mins it runs fine , then when i pull the power back to troll speed 7.5 knots it still runs fine but when im done trolling and put the speed speed up it tried to die , so then i inch the throttles up and let it try to die i will smooth out some then i inch the throttle up more till i finally get to like 3000 rpm but it still surges. any help will be appericatged thaks james

Two words "Scan Tool". I chased gremlins most of the summer when everyone one asked about scan tool check. When I did the problem was easily solved.

were do i buy one and do auto mechan ics have them and how much do they cost , thanks james