Bobcat 963 hydraulics

I'm working on a 963 Bobcat that has low hydrcharge Pressure. I have already checked the pressure relief valves and change filters. and obviously the fluid level. It will operate sluggishly at WOT but shuts down at idle. I'm fearing the pump has gone south and needs replacement. I haven't been able to think of any other possible causes. By the way it wont build more than 181psi if that helps. I don't have any flow gauges available that are large enough to accommodate this beast of a machine. Any new Ideas are greatly appreciated

Thanks