so ive pretty much had this problem for a year now. Once the boat warms up if i put a heavy load it starts to miss really bad but it will kinda clear up after i cruise under little load. yesterday i adjusted the timing and did like 20 out the hole digs and it ran great and only had a very small slight miss so i thought i had it. Here are the things ive done
New cap and rotor
new spark plugs
chaeck timing around 6-8 degs
new water separator filteri have a mallory electric ignition and distributor

also what are the best spark plug wires

thanks