2003 MSX 140, 150 flawless hours, till today.

Starts and runs perfectly but when letting off the throttle from
high speeds it just cuts off, then coast to a stop and push start
button it instantly starts and runs fine. Did a 125 mile trip today
this happened about 10 times.

good gas
good battery
good plugs
comp= mag-127, cen-125, pto-125
6850 rpm, 68mph, [on dreamometer]

Any ideas ????