'77 Merc Thunderbolt 500 kinda missing at high RPM

[hotrod53]

Overall my 500 runs great. I noticed that at full throttle it kinda feels like it slows slightly for a second every once in a while. It almost feels like a mild version of dropping a cylinder but I don't think its that, it would definately lag more if that is what it was. I have new plugs, rebuilt carbs, rebuilt fuel pumps, new fuel, new fuel lines, new plug wires, 1 new coil, all cylinders are 110# to 120# of compression, and my mixtures are where they were originally 1.5 turns on the top carb, 1 or 1.25 on the bottom carb. I might be on a 2 mile full throttle run and it may do this once or twice in that run. The motor starts right up, it runs smooth, it idles great, and I can tell that the last owner changed the stator from the shiny red teflon looking wires. I replaced the plastic piece linking the two carbs after I brioke the other one, could this have to do with syncing the carbs? Really the problem is so mild that I could let it alone and not even worry about it, just want to be sure it's right.