Stall when coming off throttle

[Janky]

Anyone ever investigate a stalling problem when coming off throttle? Specifically, when doing watersports with the kids, when someone goes down and I return to pick the up. If I come off the throttle too quickly (and especially if I come off and go right to neutral), the rpms drop and the engine stalls. If I ease off the throttle quite slowly, it wont happen, although I can usually sense the RPMs dropping below idle just briefly, like it wants to stall.

Otherwise runs great. Changed plugs, wires, distributor cap at the beginning of the season but struggled with this issue all summer.
Specs:
2004 Chaparral 204ssi. Volvo Penta SX outdrive with 5.0 GXi (fuel injected Chevy 305)

 

[Sandbar]

I know it's not a Mercruiser but if Volvo has the same components, then I would suspect the Idle Air Controller (IAC). I've been told that the Merc OEM ones tend to fail around 350 hrs. or so. I have twin 4.3's Mercs and that was exactly what I was experiencing...at ~340hrs.

I swapped one for the other to test it and when I did, the engine died as soon as I went to neutral. Replaced one IAC and solved the problem, then two weeks later the other one failed. Replaced it and no problems since.

Hope this helps.