I'm thinking sensor voltage problem

Your IAC is held in by two 8mm screws (item 38) and is on top the manifold (post 38) and just has a hose running from it to the TB

https://www.mercruiserparts.com/bam/.../31823/6708/70

I was talking about the muffler which is item #5. I have already removed the IAC and MAP and ordered new parts.
I ordered a new muffler too and I was wondering how to change it out. Basically a foam filter for the IAC located in the throttle body.

Needle nose pliers and pull it out. If its in good shape but dirty, use soap and water

Was probably the IAC. Try swapping the old back on one at a time to see which one was bad and save the other as a spare.

and if it was the IAC --- prob did not show in the scan as a fault code anyways. Great point as I had made 1000 times -- one needs to know the parameters to see where they are out of spec and that will pin point your issue a whole lot faster and easier and cheaper rather than thinking oh no fault codes - lets just start changing parts. With that said parts changing and not knowing the parameter specs - no scan tool needed a total waste of money that one can use for the parts changing instead.

I had my engine checked with a laptop I believe he had Renda loaded on it. The IAC had the engine in guardian mode and there was an older fault on the MAP sensor. I decided to replace both, my mechanic told me I probably didn't need to replace the MAP because it may have stuck from sitting over the winter or something. But I am a little OCD and I replaced it anyway. My mechanic is an old friend but I didn't know he still kept up his dealership and CEU's. Good for me he is up to date on all updates and all it cost me was a couple of beers.