1986 mercury xr6 missing around 3800 rpm ,runs perfect below that?

Check for spark. Could be bad ignition boxes, bad coils, faulty trigger, corroded wiring or bad idle stabilizer box(just remove if equipped not needed)
If engine runs normal out of water on muffs but just won't Accel in the water, more then likely carbs need to be rebuilt.
Do not buy the cheap eBay Chinese carb rebuild kit if your pickup tubes are clogged, poor machining, needles n seats and gaskets are pretty decent in those kits though.
eBay ignition boxes work pretty good.

I did a complete tune up my self 2 years ago on my 1984 150hp,

First thing to check is your fuel lines.

Could also be, fuel pump diaphragm and/or check valves.

planin' on doin' tha work yourself?.. do yo have a service manual?

Were in Wylie and can your motor out this week

How come nobody suggest checking Spark Plugs anymore?

I would check them for fire and also pull them and look at the deposits. On my 1985 175 Black Max plugs were never the issue. Maybe because they are so easy to change, When mine ran badly it was #1 carbs, #2 switch box, & #3 stator. On mine when the high side stator went out it would turn 2000 max. Is important to keep on top of the carbs on these motors. No feed means no lubrication.

Thanks guys ,going to replace fuel pump and filters again,has new plugs ,go back thru carbs ,then may try with a six gallon tank and new hose.