I just bought a boat that's been sitting since 98. I got the engine
started alright and it even ran fine for a while. 1st thing is the
plugs kept fouling with gas/oil mix so where is the flow adjustment to
stop this? 2nd thing is that when I got the engine to idle and stay
running it kept dying everytime I put the boat into gear to get it to
move. It would accelerate just barely and die. Can someone help?

Could be stale fuel. But that only affects the running of the motor.
The next step is the water pump. These are notorious for giving
trouble. Being internal, the rubber impeller could have seized and
broken into pieces in its housing and causing jammimg. It is un-usual
for the gears in the bottom of the leg to seize unless the housing is
cracked and all the gear oil has leaked out. The water pump is yourt
first step. Have a qualified outboard mechanic do the job because
specialised tools may be needed.