Cat 268B Hydraulic/throttle up problem

I am posting this for a friend who isnt very internet saavy. A customer brought him a 268b skidsteer with an issue of not throttling up. The first story is that cat looked at it and said it needed an injection pump. Going by that this mechanic removed the pump, had it rebuilt and reinstalled. Now the machine idles beautiful, here is the problem. The only way to get the machine to throttle up is to keep the arms or bucket moving. As soon as you stop moving the arms the engine will drop down rpms and no matter what will not increase rpms from an idle, until you move the arms again. When the machine idles down it sounds like the engine is laboring from the hydraulics loading up with extra pressure. Again, as soon as you move the arms the engine throttles right up.

He has searched front to back in a parts manual to get familiar with the machine and has mentioned a load sensing valve on the main hydraulic spool valve. Can anyone chime in as to what you think the issue may be?

Thanks in advance!

Cat 268B Hydraulic/throttle up problem