DF 250 AP losing speed, inconsistent rpms

[seameafterclass]

I have been having an issue for a while now, and it seems intermittent but here’s the run down. My preferred Cruise speeds for me are 4100 rpm, 32mph, 3.2mpg, or 3700rpm, 26mph 3.7mpg. It will be driving along just fine, and all of a sudden there is an audible change in the motor and the boat drops in speed from 32-24 or 27 to 19, while either maintaining RPMs or increasing. It almost sounds like it’s the VVT kicking on and off. I had the O2 sensor replaced 1-2 hours ago. I got a phantom beeping code, but no codes on display, the motor started running very rough when the beep came on. Turned batteries and motor off and restarted. Seemed to run better but a little jerkier than usual (spark plugs replaced 40 hours ago) motor has 440 hours and is a 2015 with fly by wire.

only other issues I could see contributing: I got a few IAC codes a few months ago, but it only happened on one or 2 trips. Also I noticed a small tear in the skinny hose going to the VST from the top of the motor (I think it’s a return line from the fuel injectors)

anyone else with inconsistent performance/running?

[redlowrey]

If you have electronic throttle control, you won’t have an IAC valve, the thin hose will be the vapour line going to the evap vacuum module.

If the variable valve timing was out of spec with the cam sensor, the check engine light would have come on.
If the rough running was from out of spec cam timing the light would definitely be on.