Mushman:
Before you do anything, I recommend you change all of the spark plug wires. I had the exact same problem and symptoms with a 1989 Evinrude 200.
Powerpack, coils, etc., were suspected (and changed), but the answer turned out to be much simpler and cheaper. My wires looked fine, but several had developed invisible cracks in the insulation which allowed them to arc (ground out the cylinders to which they were attached) at high speeds. Consequently, RPMs went down, and the spark plugs on those cylinders always appeared wet. At idle and low speeds all cylinders had spark, and everything looked fine.
A quick test that will generally confirm an ignition wire problem is to spray all of the wires with silicone, then take a run. The silicone is usually enough to fill any insulation cracks for a short while, so if the engine runs fine, you know it's the wires.
I hope that's your only problem. Under any circumstances, changing the wires every few years is good preventive maintenance.
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