Mercruiser 5.0L carb, idles now, but bogs down at lower throttle & then rpms jump up

[Maxumillion]

6/2014 Update: Brewer Dauntless Shipyard mechanic finally "adjusted" the carb for a 2nd time in a year's time, engine now idles but the idle was set to 1,000 rpm in error based on what I've read, which should be @ 650 like its twin is running. How they thought it was ok to have it so out of synch with its twin & out of merc spec is beyond me, but par for their course thus far.. So I lowered the idle, but other problems still exist that Brewer claims was fine when tested:
Problems are as follows:
1) hard & rough start req'ring rpms above 2K until fully warmed or stalls repeatedly, unlike its twin.
2) bogs down & wants to stall when throttled up slowly or quickly in either neutral or in gear. Hear air/sucking sound as it bogs.
3) when throttle is pulled back as it is bogging to prevent stall, the rpms then jump way up to where the throttle was just prior even tho its back to idle position.
4) upper rpm range is totally fine & runs strong thru 3K's
Anyone have this issue or know of an easy fix, ie fuel/air mix etc??
Thanks...