Outback feels rough and losing power on throttle

Hey All!
Well today was the first day of getting the 07 Outback into the water.
I always felt that when we purchased this boat back in 2017 that it felt a bit rough in the water while driving but today if felt more rough.

So unit was in dry storage (heated garage, washed and put away until today, nothing else was done prior to putting it away into storage)
fired up with 1/2tank gas no problem, topped up with new fresh gas.
Put unit in water and ran it, no problem getting up to speed however it feels almost like a cavitation I am having? It feels like a vibration and cavitation sound when running at around 15-20 on the speedo. I was watching temps and feeling the manifolds. The starboard manifold was cool where the Indmar stamp is but the riser was quite hot, after running the boat a bit more they both seemed to even out in temps and were just warm. My temps on the gauges were:
Battery 14
Oil 40 (at a idle state)
Temp ~157(center gauge)

What I was noticing when driving was we would be cruising and I would get this cavitation sound and slight vibration and I would start to lose power until I throttled very slightly more and it would improve.

Could a bad water pump impellor cause this? Or would I see I spike in the temps vs. What I see?

Can we run an octane boost in this tank of gas to blow things out?
Beginning of last season I repacked the drive shaft knuckle

Possibly your prop has lost it's pitch? If its ever hit anything or been through sand.

Sent from my SM-G781V using Tapatalk

Spark Plugs!
Cruising along then you mis-fire, lose power throttle up which adds timing and it's fine. Back to cruising, mis-fire, repeat.

Is your 2007 the 325 assault motor? I would guess plugs, cap & rotor. Probably have moisture from condensation in the cap also.

Your temp at 157* is perfect.

I would be nervous with putting a boat away with 1/2 a tank in fuel. Even if using fuel stabilizer that is a lot of open space for water moisture to develop. We always top off the tank and add fuel stabilizer before winterizing.

I came from jet boating world prior to vdrive, so I’m well familiar with the term cavitation and how it feels. Reminds me of a slipping clutch in a manual car or tires spinning in mud. If it’s truly cavitation you feel and vibration I’d have to assume something is off with your prop. Have you tried swapping props just to see if there is any change?

Would it be worth it to add in a fuel stabilizer?
I will order up some new spark plugs for that it's worth.
It it's moisture is this something that will go away or is there something I need to do?
I don't have a different rotor to put on and check so I can't determine if that is it.
But yes to holdmybeer we would be cruising and feel like a loss of power and at that time we would have a slight vibration through the boat.

If looking at a new prop what is a good one to look at? I understand there is alot about different pitches etc



I do have the 325 assault motor

325 assault is based on the GM Vortec 5700 engine platform. 1998 truck engine has the same cap & rotor. Spark plugs for that engine will also be the same as your boat. Should be able to get everything at a local auto parts store.

Are there certain lengths of cables I should look for? Mine are the red Indmar ones. Or should I just focus on plugs and a rotor replacement?

Wires could be bad. Not sure what should test at for INDMAR specs. But you can test the resistance. If you get 25ohms and the wire is 1ft long then you know the rest should follow suit.

Sounds good. Thanks for all of your help

I'll start with plugs and spark system and work my way up from there.

I'll look for some 41-101 plugs(.45 spacing) and a rotor

Does your distributor cap look like a flat spider or is round with terminals on top (standard)?

Again, these parts can be sourced at a local auto parts store.