symptoms: when starting out from idle upon opening throttle, boat
vibrates and rattles but fails to produce adequate thrust. Prop turns
but only generates minimal movement through the water. Engine revs at
high rpms but fails to accelerate through the water.

Attempted Fixes: rebuilt carberator, flushed the fuel, replaced fuel
filter, replaced the batteries, replaced the starter, replaced 12v
coil, replaced the ring gear on fly wheel, replaced the coupler, even
replaced the spark plugs.
Note: when replacing the gear on the fly wheel, engine was pulled and
replaced, without removing the stern drive

Note: Boat was purchased roughly 1 month ago with rebuilt engine and
currently has 62 hours on it.


Possible Diagnosis:
could be ignition
could be drive unit slippage
prop cavitation / ventilation

Still searching for an answer. Any help that could be provided would
be greately appreciated.