1995 3 cylinder 60HP problem

I ungraded from a Jon Boat to a wide Stumpknocker. It came with a 1995 3 cylinder 60HP Merc. I had the same engine on a boat years ago and it was a good one. When I looked at the boat they guy started it and told me it had not been started for a couple months due an injury. It started right up but was running a little rough. Anyway I bought the boat/motor.

I got it home and started messing with it on the water ears and noticed it seemed to down on power. I checked fire to each cylinder and #3 was out. I replaced that coil and yep it had good power again. I put new plugs in it at the same time. Replaced the fuel filter although it was really clean. This motor has a pop/miss fire on occasion. Not consistent. Knowing it had set for a couple months I went ahead to pulled the carbs for inspection. All were super clean. I ran a fine wire into every orifice while I had them apart and blew out with carb cleaner. When I got to #3 carb I noticed the float was almost half full of fuel. I thought "that is the problem." I bought a new float, set the float level and reinstalled back on the motor. Started it up on the water ears and I still am having the same problem. It starts instantly, idles decent buy when I start to bring the RPM's up I hear a pop then a puff of smoke intermittently.

It starts, runs on all 3 cylinders and has good power. The pop/miss fire is driving me nuts. I read hear that it is better to run 2-strokes with the motor in the water so I took it down to the nearest ramp, backed it in, started it up and was doing the same thing except a bit quieter. lol

I am not mechanically challenged and have built many a hot rod over the years but obviously I am not a Marine expert. Help or suggestions would be appreciated.

Just an update if anyone cares. Today I went through the carb sync, linkage adjustments, and did timing at idle and WOT. While doing the linkage adjustments I noticed the linkage had to be forced to get the idle cam to line up correctly. After doing the timing adjustments it allowed all the other linkage to be adjusted per the book. Idle timing was 5 degrees off and the WOT was about 10 degrees off. Hooked it up to the water and it fired right up but still has that bit of pop/smoke issue. It doesn't seem to be as bad but then again maybe it's wishful thinking.

Update #2. Took the boat out for the first time day before yesterday. The wife wanted to do some cat fishing (love that woman). lol Unloaded and tied off to a floating dock. Parked the truck and trailed and jumped in. Put the boat in reverse and it went forward. lol Caught it quick and put it in forward and backed out. We then started out across the lake gently at first, slowly building up speed and confidence. I had the motor trimmed up too high and when I pushed the button to trim down nothing really happened. I slowed down and was able to trim it down. I had this same motor/trim combination on another boat and never had this problem. BTW, the guy I bought the boat from had just had a new trim motor and cylinder installed before I bought it. Anyway trimmed down and went fishing. No luck, bad day but got to check the boat out finally.

Back to my original post. Going out I did hear it pop a couple times though the exhaust but not much. On the way back in with a storm approaching I decided to run it a little harder. The boat is a wide body 16 foot 4 inch Stumpknocker. 83 inch beam width. Water was starting to get a little choppy but no white caps. I got it up to 23MPH and eased into it a little more each time till I reached 30MPH. I had a little left but not sure how much when I dropped back to 25MPH the rest of the way. Never heard the engine miss all the way back. I was happy with that.

So, yesterday I dropped the foot and aligned the shift shaft up as it should be and forward is forward now. lol

Any ideas as why I can't trim down while running half throttle? I understand the additional force being applied to the motor to resist the electric trim but think it should still work.

Recap on what I found on this boat before I put it in the water.
1. Only ran on two of three cylinders. (Bad coil)
2. Found the bottom carb float to be half full of fuel. (Replaced. The old one is still half full after sitting on my bench for a couple weeks. lol)
3. Upper motor mount bolts were loose/frozen. (Removed powerhead and had to cut the old one out a piece at a time. Bolts corroded into bushings. Replaced mount and bolts)
4. Re-sync'd carbs, set idle and WOT timing.
5. Forward was Reverse and Reverse was Forward. (Aligned shift shaft to proper position)

I think that was about it. I may have forgot something.