1998 Marineer 50 HP 4 stroke 4 cylinder

I recently rebuilt the carbs and took the boat out for a test run. The engine starts great and will run at full throttle 5800 rpm sounds great. Then after a little while it get a kind of miss and it throttles down to 4200 rpm and will not do any better. If i stop for awhile it will run great but it goes back to the miss and lower rpm. Is it possible the the control unit is bad and is there a way to test it. That unit is $450 and I cannot return it if that is not the problem. I have checked out every possible thing that I can carbs, fuel pump, stator, coils and they all checkout good. Please help!!!

Rev limiter kicking in ???----------If so try a prop with 1" more pitch.

racerone said:

Rev limiter kicking in ???----------If so try a prop with 1" more pitch.

Click to expand...

I changed the prop and went to a 11 pitch and that helped but it still drops rpm after a short time running. Rev limiter is there a way to check it and where would I look for it?