Need Help. (posting here as well as on the FB group) Boat has intermittent power loss and sometimes even dies. I'll try to be as specific as possible. It's a 2008 Moomba XLV with the 340 CAT ETX engine.

Towards the end of the summer, the boat developed a problem where it suddenly lost about half its power and would cap itself at exactly 3,000 RPM's. This problem was VERY intermittent. Some days it'd run perfect. Others it'd run for 20 minutes then have this problem, then the problem would mysteriously go away and the boat would run perfect again. When the problem materializes, the boat's RPM's would surge and eventually settle to exactly 3000 RPM's. When I've run it on the hose, the Fuel pressure at the rail was in a normal range but the needle would surge with the RPM's of the boat.

Last week, the boat had trouble starting a couple times, and ultimately the 2nd time it wouldn't start no matter how long I cranked it. I really felt like it must be the fuel pump and replaced BOTH the low pressure and high pressure fuel pumps. Ultimately we couldn't even keep the boat running (if it would even start) and had to get towed 7 miles to the dock.

Today I took it out and after 20 minutes it had the hiccup where it lost power and capped itself at 3000 RPMs. And then it ran fine for a while, and then it was back to low power and 3000 RPMs. It did this on and off the whole time it was out. Toward the end of today (we were just floating near the launch by this point) it started escalating to where the engine quit a couple times (we got it on the trailer ASAP).

***There are NO CHECK ENGINE LIGHTS*** Never has a CEL ever lit up. (just to be sure, I ran the engine on the hose and unplugged a couple O2 sensors to verify that the CEL does in fact light up). 2 years ago I had surging but it was different where the boat wouldn't even get up to 3000 RPM's and a CEL did come on with that one and it was ultimately fixed with all the tuneup stuff (including wires).

Here are the things I've tried:
- Replaced fuel filter
- Seafoam and Heet
- Replaced Spark Plugs
- Replaced Cap & Rotor
**I did all of the above, as well as the plug wires also in 2016. (that said, I believe I've been putting 150-175 hours on annually)

I do have a squeaky alternator that I haven't replaced yet, but my charging voltage is never low on the gauge. Oil level is fine and oil pressure is not low (it tends to actually be on the high side). Engine temp is fine.

I'm running out of time to be able to get it on the water, so I don't know if I'll even be able to fix this before I have to winterize.

I talked to the dealer and they said that they'd have to put the boat in the water and replicate the problem to diagnose. But it'd been so intermittent that I just saw that as money flying out of my pocket.

I'm wondering if it's a sensor??? (Crank Position? Throttle Position? Engine temp sensor?)