Seadoo Challenger 1800 stalls and makes noise beyond 25-30 mph

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Suededog

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Help!!!!Seadoo Challenger 1800 stalls and makes noise at 4000 rpms

I know there are numerous other posts with these same issues discussed in length, but I have read them all and have tried to test a lot of what is mentioned in those posts with no luck. Please throw me some feedback or experiences if you have any. If you saw this post earlier I have tried and replaced a few more things and edited them in.

Here goes:
I have a 2000 Seadoo Challenger 1800 with a 2003 Mercury Marine 240JD EFI engine. I haven't owned the boat long, but on the test drive and the first 4 1/2 outings in the boat everything ran GREAT. No bouncing up in down in the front, no pulling to either side, starts first crank, great acceleration with no missing or bogging, 62 mph top speed. THEN after being on the lake for hours with everything driving great I noticed all of a sudden at full throttle that I was at 40mph. I stopped and looked everything over and tried to take off, this is where the issue begins. Everything still starts fine and if I ease into the throttle slowly I can go about 25-30mph with no issue. As soon as I go any further on the throttle (around 4000 rpm) the engine starts bogging down and making a lot of noise (kind of grinding/spinning sound possibly, my first guess what that it was the impeller spinning out not sure about though just kind of what it feels and sounds like) If I don't go too far with the throttle once it messes up I can ease back off and still run fine at 25-30 mph, but if I go full throttle it bogs to a complete stop pretty much (note: engine never actually dies and always starts right back up if I do turn it off). If I go full throttle and cause it to bog I usually can't get it to run even at slow speeds/low rpm again without shutting the engine off and immediately restarting. Once I do that again I can cruise 25-30mph with no issues, but the noise/bogging still happens when I give it more throttle beyond 4000 rpm.

What I have done so far:

Changed the plugs

Changed fuel filter (water sensor oil filter looking one, have not changed metal filter that goes into primer pump, but I took it off and it appeared in good condition)

Bleed air from engine mounted oil tank.
Checked the anti syphon valve seems fine blows one way and sucks the other.
Checked as best I could for any signs of an object in the impeller area or any signs of damage to impeller or wear ring. Never saw anything in it and to me the impeller and wear ring housing (I have the Mercury metal housing style not the replaceable plastic ring) looks fine. No nicks in blade and no damage to the ring. It seems to be really tight fit as it should. I can reach in from the bottom and rotate the blade freely but it is tight which I assume it should be.
I checked all grounds and wiring and the one fuse that I could find in engine compartment and under driver windshield. There are numerous plugs and wires that aren't connected, but that has been the case so that could be the issue but I don't think so.
Took fuel pump off and blew thru holes but they didn't seem clogged to begin with. Springs and all parts and filter and o ring all good.
I have pretty much checked all hoses, connections, filters, valves, and parts from the fuel tank up through the fuel pump. I haven't checked beyond that point I don't think.

With my limited knowledge and from researching it seems to be either an impeller issue or lack of fuel. What would be the best place to check that fuel is getting all the way thru the path and getting to where it needs to get to beyond what I have done? Does this even sound like a fuel issue? Or impeller issue? Like I said impeller and housing looks fine and never had anything in it from the time the problem started as far as I can tell, but it does kind of feel like and sound like what I would imagine it would feel like if the impeller was just spinning out when my issue kicks in at 4000 rpm.

One more thing I have noticed is a possible shifter/throttle issue which I have read about being causes for certain things. I've never really noticed anything wrong with it before all of this, but on closer attention it does start while out of neutral. It will not start if it is completely in F or R but it will start if it's slightly in forward and it kind of pulls it into neutral as it starts. I kind of assume that part is normal and had never noticed it really. One other thing if I lift up a little on the cam lever while in neutral to rev it up a little a couple of things happen occasionally, not always but sometimes it will force it to go into F (this may be normal if it is raised to a certain point I don't know?) the other thing that sometimes happens though is as I rev it up it gets stuck and the only way to make it rev back down is to kill the engine. Then you can immediately restart without touching anything and it is no longer reved up. Could this be related?

Any suggestions would be greatly appreciated! Please let me know if you need more info and I will do my best. I do have a shop manual for the engine and the boat as well as the owners manual for the boat. I'm no pro for sure, but I've got an 1986 Mercruiser that I have kept alive all of these years and I have ridden 2stroke motocross bikes all my life, so I'm pretty decent at figuring things out if pointed in the right direction.

Another thought was carb issue, but would this be likely right in the middle of driving all day with no issues?
 
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