I have a1982 90 Johnson. Cleaned the carbs, new spark plugs and sprayed sea foam spray in it not the stuff you dump in the gas.it comes in a blue can and costs 10 bucks at menards. It's meant to clean the Pistons and cylinders. Runs great now.

(Carburetor Adjustment - Single S/S Adjustable Needle Valve)
(J. Reeves)

Initial setting is: Slow speed = seat gently, then open 1-1/2 turns.

Start engine and set the rpms to where it just stays running. In segments of 1/8 turns, start to turn the S/S needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running.

Eventually you'll hit the point where the engine wants to die out or it will spit back (sounds like a mild backfire). At that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.

When you have finished the above adjustment, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.

Idles rough

I've now tried all this with no improvement. I've also run copious amounts of Sea Foam through it with no change. It still starts easy but idles rough and runs rough until I get to half throttle and then it smooths right out and runs great. It's just the idle and the first half of the throttle that's the problem. What could I do next?