Forum Wizards:  The good news is that it has been quite a while since I had to past a question here.  The bad news is that I need to now!

Here is the situation:  Only 1 cylinder in the motor is firing resulting in sluggish (basically half) performance.  Here is the history of the situation:

1. Took boat and it operated for about 8-10 miles able to go at full speed (24MPH) with no issues. Start to head back to boat launch and suddenly top speed is like 8 MPH.  So we puttered back for as long as it took.  Figured it was a spark plug issue so took boat out of water, changed spark plug, put back in and it ran fine at 24 MPH.  The one spark plug I did notice was bone dry at that time which caught my attention…
2. Boat in garage for about 6 weeks…then take to another lake, put in water and back to running at 8-10 MPH.  By this time I had ordered a 10 pack of spark plugs.  Since I was at a boat show, decided I would put 2 new plugs in and giver her a try – same thing, half the performance.
3. Attached is the picture of the spark plugs I just took out. The left one is from the upper chamber and seems very dry comapred to the right one (bottom chamber) that looks wet which is what I expect.
4. I also have attached a picture of my fuel pump which this forum led me to which was a gamechanger as far as performance this past year.  That thread I started on that issue can be found here: Topic: 1956 Johnson 30hp High Speed Tuning – Antique Outboard Motor Club,Inc (aomci.org)

Any thoughts on how I can attempt to triage the situation?  The pump is serviceable and did come with some spare parts.  Or perhaps a clogged fuel line?

Many thanks!

Rich