OK, rereading the posts the two things that really stand out are that you need a higher throttle % on the port engine to achieve the same rpm (3200) and the the famous FJDT test indicates that port is not achieving the same power as starboard at WOT. I would proceed with some confidence that you either have a dead cylinder (ignition or injector) or perhaps a leaky one (burnt exhaust valve or slow closing valve). This would explain everything and while the power reduction would usually occur at all rpms, either problem could only show up only at higher rpms. Also, from experience I can tell you that dead cylinders are very hard to detect by noting a power reduction at lower rpms (the boat speed helps keep the weak engine turning) or by listening at any rpm, although in my boat they can be detected at idle by a rattle in the flex plate.
A bad injector is unlikely since you had them serviced, and since that should not increase fuel consumption on that engine.
So if you buy all this you can start by doing a compression test (which will point out the most likely valve problem (a burnt one), and will allow you to inspect the plugs). This would be my choice. Or since you believe the ignition is suspect, you could start by inspecting to insure each plug wire is firmly attached and there is no carbon tracking or cracks in the distributor cap. Then move on to swapping ignition components (coils, distributor caps, wires) between engines to see if the problem moves (or simply goes away since removal and reinstallation on the other side sometimes corrects connection issues). One of those two approaches will likely identify the problem.
