Our wb 150 will bog down and smoke black a good bit when you do 2 hydraulic motions at once. If your at a low throttle it will stall out to sometimes? What are the common things to look at, beside checking filters. Will it smoke black with a clogged fuel filter?
Clogged fuel filter won't cause excessive black smoke, will cause stall. Clogged air filter will cause black smoke as well as failed turbo. Could also be something in the hydraulics causing excessive load on engine and engine is trying to compensate for load by cranking all the power it's got. Just a couple of thoughts.
Ill check the basic stuff in the next few days when i get a chance to go to the machine.