Sport jet 90 runs rough

[backwater dawg]

I have a 1994 Merc sport jet 90--I know it's a Force outboard power head--It was running rough and I put new plugs in it and it's better but still a little rough--I ordered new wires--that should help also--My question is??? is ther anything else that I could replace to give it a little better spark and more power--do coils get weak?? it is 13 years old---I have replace all the other electronics---thanks