what kind of engine is this

2000 Johnson
Carbed
150hp

tat engine doesn't have a computer per se, but it dies have electronics that will derate the engine from over heat or low oil. It should give you an alarm if either of these are occurring. Start off by checking the alarm circuit. Does it beep when you turn the key on? Find the temp switch on the cylinder head, ground that wire with the key on, it should sound an alarm. If the alarm is working, and your loosing power while running, next thing to do is run with a portable fuel tank. If it runs good with the portable, look at your fuel system. If not, Id check the electronics on the engine, most likely the powerpack. If you can get it to act up on a regular basis, you should be able to ground out one plug at a time and see if its related to one cylinder or another. If you are still suspect to an overheat issue, buy a temp gun from harbor freight, they are cheap and help a lot with diagnosis. Once you confirm its not overheating, you can disconnect the temp sensor and see if it does it again(bad sensor)

Sounds familiar to me I had the same thing happen to my Mercury, I would be driving then the RPms would cut in half and my oil alarm would sound that happened for about a month Running great than RPMs would cut in half, what it turned out to be was I have two power packs and the one that the alarm was hook to would stop working causing the RPms to drop if it happens on land check for spark your probably losing half your sparks to the plugs Like spare said check your power packs Good luck

Thanks Guys...I'll get back on it tomorrow

Bill