I am working through similar problems with my Turfcat.... I have been told to check all the injectors and lines for tightness, and any fuel line (rubber) for cracks or wear. Maybe one of these will help. Good luck.
I own a 90XT also. The fuel shutoff uses an electric solenoid that I have had go bad before. It could be going out. I also found a very small leak in the fuel hose from the tank to the fuel pump. I was very lucky to find it because it was lightly misting fuel toward the exhaust manifold. We had to remove the oil cooler and radiator just to replace the rubber fuel line.
Good Luck
