2004 60/40 jet not getting top rpm

[rynonugget]

60HP MERC
CARBS ARE CLEAN JET IS FREE. IDLES FINE.
LOST TOP SPEED ...GOOD COMPRESSION 120 IN ALL 3
DISCONNECTED EACH COIL WHILE RUNNING ALL DO MAKE A DIFFERENCE.
SCRATCH MY HEAD ????
IS THERE ANYTHING IN THE IGNITION THAT WOULD ONLY GIVE YOU HALF THROTTLE
RAN MOTOR WITH COVER OFF ..MANUAL PUT LINKAGE AT FULL THROTTLE ..IT WAS THERE ANYWAY ..STILL NO TOP RPM.. RUNS OK ..NO MISS OR SPUTTER.
JUST ALL OF THE SUDDEN . LOSS OF POWER.
NEED HELP. Mike

[boatmangc]

Maybe your high speed timkng adjustment screw jam nut loosened and the screw moved and is preventing your timing from fully advancing.
Check your timing without the motor running at WOT.
There should be a sticker on the flywheel cover that tells you what it should be at at cranking speed.