86 Merc 200 missing/loading up under acceleration

[Phil L]

Kind of a strange intermittant problem I am having, that I am hoping I can get some insight on. I have a 86 200 black max. The last two trips I have ran, once on each occassion, the motor has either missed or loaded up(i.e running rough) from 2000-3300 or 3400 rpms while giving the motor throttle. On the first occassion after fishing all day, ran the boat inshore and stopped and made a few more drifts....when coming up on plane to run home, motor ran rough during acceleration....ran fine at idle and slow throttle and fine at cruise rpm 3800-4000. After coming in and coming off plane, throttled up a few more times and problem was not apparent. Second time fished all day, ran in stopped for a sec, took back off and problem appeared again....ran fine at cruise rpm....again cleared right up as I throttled the motor up several more times that day.

The issue seems very intermittant and only during coming up on plane from a standstill...the motor idles fine and seems to run fine at cruise....

I am going to change out the fuel filters and pull the plugs and look at them and change them out....looked at the bowl on the fuel/water separated and no water present.

Other than what I am proposing to do, any other things I can look at....I do have a shop manual and can test.....

Thanks for you help...
Phil L

[vector mike]

My guess is the needle and seat. Might have a little piece of dirt in it.