Cat 305E intermittent slow stick in and slow right swing

The problem comes and goes a bit- when it happens it feels like the joystick is part way engaged (moving at half speed) when in fact the joystick is at the maximum. You can hear the pump is not stroked fully... Most of the time when you stick out or swing left then go back it goes away for 10 or 15 times of those functions but then will randomly slow again. Pump? Valve? Pilot? SN 305EAXFA00348