1985 yamaha 90 hp 2 stroke 3 cylinder outboard surging at full throttle

Hi,
I'm about at the end of my rope with this....Motor was running fine, no problems known. I launched the boat , started and idled out of the no wake zone and when I pushed the throttle down, the motor stuttered and shook back and forth. As soon as I took it back below 1000 rpms it ran good enough to get back to the dock. Upon examination, I discovered the old fuel line had started to deteriorate and was clogging the connector and some chunks had gotten into the fuel filter. Don't think any chunks made it to the carburetors. At any rate, I replaced the fuel line with new stuff, thoroughly cleaned the filter, new fuel pump,new spark plugs, cleaned the fuel tank and put in fresh gas. As a final precaution, rebuilt and cleaned all three carbs. So now the motor starts but still won't go beyond 1100 rpms without surging and shaking, acting like it's fuel starved. I suppose it could be an ignition problem but I did a compression check-all good, checked spark-all good, coils- all good. I can't believe this isn't fuel related somehow because it would be too weird to think the fuel lines went bad at the same time I had a bad coil or something. Anyone else have this happen, help!

Replace the filter, don't clean it. Also check for restrictions in the fuel lines between the filter, pump and carbs.

After you notice the problem, is the primer bulb still hard? If not, make sure your fuel tank is venting properly.

Thanks for your response. Turns out it was a bad coil on one cylinder. I screwed up when I was testing the spark the first time, checked it again and no spark. Anyway I feel like an idiot for not double checking the obvious, at least I finally figured it out!