I don't know if this is your problem, but:
I have a 1996 GTX and it showed similar issues. What I discovered is that the fuel lines that the manufacturer used were type B. The ethanol added to our gasoline had degraded the fuel lines and the interior of the lines was sluffing off and clogging the carbs.
We ended up replacing the fuel lines and the fuel selector switch, rebuilding the carbs and cleaning out the gas tank.
Jetskier