05 900 fuel prob & other issues

My Fusion 900 started having fuel issues last year. It would start 2-3 pulls, idle up and run fine on the trail however when I held it at WOT on a lake it would starve itself for fuel before it reached top speed. When backing off and holding it at 3/4 it was fine. Did that for multiple rides then sat for a week tried to start it and it took several pulls, backfired then started on next pull idled up but when it idled down it ran like it was on 1 cylinder then died. Every re-start was the same. I changed fuel filter multiple times had fuel pressure tester on it @ idle when it was idling fine and it was @ 58#s same reading when it was idling like crap ( had to keep feathering throttle to keep it running ) Couldn't check it while riding because length of tester being too short. After leaving tester on over night it was losing pressure and it steadily dropped every day but with a few pulls it would pressurize fine and start ( like crap ) but remain at 58#s.

Now I have read multiple posts and there seems to be several things that can cause this, one of them being a bad TPS or pigtail. Replaced both with no improvement.

Sled needed some maintenance so I pulled motor to replace mounts and found a lightly scored mag side piston. Also the fuel rail connection above the pressure valve to tank was very weak (easily pinched when bending) .

So seeing all these issues I decided to replace many parts that seem to have problems and have been updated.

Rebuilt engine, top end, crank trued, pto bearings and all new seals.(2200 miles)
New motor mounts.
New TPS.
New fuel rail.
New stator.
New wiring harness.
New fuel pump and regulator.
New voltage regulator.
Injectors sent to Indy Dan for testing/cleaning.

Now this project has been in process since October and I'm told Polaris is having trouble with inventory. Cant seem to get a solid answer on why I'm not getting parts, getting partial shipments then partial shipments on my partial shipment. Frustrating to say the least.

Any other suggestions or tips are surely welcome.

Bought sled new in 09. All updates were done. Yes tank has white floats.

Checked flywheel when motor was pulled and inner sheath was coming loose so I epoxied it back in place. It did not cut any wires on old stator and yellow wires on stator were still epoxied in place with no breaks.

I am waiting on fuel regulator and main wiring harness. Hoping that takes care of any broken or corroded wires. I will check old harness wires to see if that is a problem. When I bought sled I used dielectric grease on all connectors.

Can the ECU be tested while it is out of sled, and can capacitor cause any issue?

I should mention that I have been fighting an over heating issue with this sled from day one. Bled system even had to replace coolant bottle 3 times, was told the filler opening was warping out of shape and not holding pressure. So I am curious if this fuel issue is related to that. I stared opening hood every time I stop for any length of time to dissipate heat more quickly and it has helped, got entire season out of last coolant bottle.