I have a 99 GSX RFI. It starts the first time in water (sometimes) and I can drive it around all day, however once I shut off it will not start again only crank. If I lift the exhaust out of water or back on trailer fires back up. I have been through most of machine and now I am lost. Here is what I have done

New plugs and trim back wires
New fuel pump/filters/gas/injectors professionally cleaned by injectorrx/ (tested on install 59psi and drip test no drips)
Rectifier, starter, battery new
Oil flushed, new filter and tygon lines to rv cover using seadoo synthetic red oil
Rotary valve and new cover and are within specs of manual
No fuses blown. MPEM connections seem to be corrosion free.
Compression was in the 150-155 area both sides
Throttle body cleaned and tps reset with candoo
Raves cleaned

Over the weekend I did an ohms test. Everything checked out except the water temp sensor and air sensor were a little low. The injectors were a tiny bit high. Here is my result:

Water Temp Sensor. Should be 2280-2736 ohms was 2010
Air Temp Sensor Should be 2280-2736ohms was 2060
Injector 1 and 2 Should be 2.3-2.5ohms both were 2.7
Air pressure/ tps/ crank position sensor/ rave solenoid/ and coils all seemed to be within spec.

Could it be a ground wire? Could the water air sensor be problem? New rectifier I have could that do anything? I have been through most of this ski and I also checked for delaminiation or restrictions in exhaust I don't see any. I see some old forums with some people having same problem no solution.

Something changes when you put back pressure on the exhaust it seems. Is there a back flow baffle in the resonator?? If I move up the rv a few teeth would that help? This thing runs excellent once it is on but this no start thing is beyond frustrating. Someone I am sure has had this problem!! I am new to working on a jetski and just going by what the manual says as best as I can. Thank you for your time.