This is from the 1998 Seadoo GTX RFI shop manual:
ENGINE STARTS BUT RUNS POORLY:
If the engine starts but runs poorly, the following items should be verified in this order:– check spark plug condition– check fault codes in the ECU memory– check fuel pressure– check TPS adjustment
If some work has been performed on the unit,make sure injector wire connectors were not mixed.
It is also possible that the RAVE solenoid connector be mixed with one of the injector connector. Refer to the wiring diagram for wire colors and positions