Okay so the motor is a 502 MPI Gen VI.. I just got finished doing pretty much the entire top end, new heads, intake, EMI thunder exhaust etc.. The bottom end supposedly was just fine.. anyway so everything is done and the boat fires right up with no issues, compression is good, oil pressure is good etc.. idles great, throttles up just fine and then as soon as it hits around 3000 rpms the motor just shuts down.. then i try to restart and it seems really weak and doesnt crank over.. it cranks but then just whines out and wont turn over.. batteries are fully charged, alternator is just fine... Once it cools down it'll start right back up but then shut down once reved up.. I'm out of ideas.. I need some help from you Gurus out there..

Thanks Guys

Check your ground connections first. I assume they where on back of one of the heads you replaced.

I checked them, they are all good.. i'm def thinking its something electrical with either the ECU or the ignition