need help: breaking up, loosing rpm when running hard
 

I have NA Carbed 540's with msd ign, and electric fuel pumps. the motors idle fine, and run awesome up until about 4000RPM and then they seem to intermidantly cut out to about 2500-3500RPM. sometimes when cold i can run right up to 5300 with no problems. problem gets worse as the motor gets warmer. already put new fuel filters, and swapped coils from one motor to another. richened her up a little also, but nothing has helped yet. when i went to start the boat sat morning i turned the key to the on position and the fuel pumps went on like normal, but then when i went to the start position there was nothing. after messing around with the key for a minute she lit right off. i am going to jump my ignition wire straight to the battery and give it 12 volts. maybe the actual key switch is going bad????