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STX15F wont rev above 5000 rpm, advice needed

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  • STX15F wont rev above 5000 rpm, advice needed

    Hi all, I'm new to the forum and I have an issue i was wondering if anyone could assist with.
    I have a 2007 STX15F and im having issues where it wont rev above 5000rpm in the water however if i spin it into a 180 at full throttle, when the jet pump comes out of the water it revs out to 7800rpm. As soon as the pump hits the water again it drops back to 5k rpm, but im assuming thats just the ecu not able to compensate for the full load to no load quick enough to keep the revs at 5k rpm out of the water. The ski runs perfectly smooth apart from an off throttle back fire occasionally. I've been throught the be all end all list of smokeysevin and alittle more with no success so far.

    I have new spark plugs,
    new 4 in to 1 exhaust piece
    emptied the old fuel and cleaned the tank. then filled it with 98 octane and some fuel doctor.
    Ive stripped the pump and it spins freely and doesnt catch anywhere and overall is in very good condition.
    Ive also serviced it with new oil, oil filter and fuel filter. Pulled and cleaned all sensors apart from crank angle.
    The pump flows 150mls with a single start button press which is well within the 67mls spec.
    The sensors tested as follows between 20-30 degrees C:
    Water temp - 228K ohms
    Oil temp - 233K ohms
    Air temp - 1.85K ohms
    TPS - 5K ohms total with the individual legs responding proportianally to the movement of the butterfly.
    Cam sensor - 417.7 ohms
    Crank sensor 527 ohms.
    Injectors are all spraying and all 12.3-12.4 ohms

    All cooling lines are clear and i can blow through the entire system no issues. it also has a Riva intake, good flow out the pisser and doesnt do anything else that i find odd in terms of the way it runs. It feels like its deliberately limited to those revs, like its in SLO mode as it makes no difference when i change between the two modes. the only thing i find alittle off is the fuel pressure registering 39psi when im holding the start button in and the injectors are firing but if i just tap the start button and let the fuel rail pressurise, itll go to 42psi. Also the display, it wont register speed as the display is not outputting 12v power to the steering sensor or speed sensor so im sceptical about the integrity of its internal circuits.

    I was wondering if anyone has come across and issue where the display is telling you that it has changed to FPO but it hasnt carried out the command at the ECU level? obviously my MFD is faulty so I'm after any feedback in regards to this 5000rpm SLO mode type issue im having.

    Thanks guys