IMO after reading your post more in depth - and this is not stock and possible the tune is not stock - when the apps are not stock a lot goes out the window.

Possible bad IAC and or connections

If not fixed then possible bad coolant temp sensor and or connection / wire.

Possible might be hard to get an OEM certified VOLVO PENTA shop to work on this app.

Is this a saltwater app ? check all grounds as well


Good luck with it.

Thank you all for the information. I really do appreciate the insight..

So, yes the plugs are the ones that Whipple recommends. I had to ask the shop to verify this when they replaced them 5 hrs ago. Again, the frustration is that the boat runs well now, with no alarm, which is why I am leaning towards a failing part. Does this make sense? Or could it have been the elbows overheating and causing the computer to go into limp mode?

Lastly, there was one minor detail I forgot to mention, a few runs before this, the motor spit the raw water pump off the front of the crankshaft a few runs ago. Shut down immediately, checked compression and all was fine. No water in the oil. Got a new pump and added coolant.