Troy-Bilt Z809H, 24 HP B&S engine, 46" deck,

With the engine off, everything seems fine. I can shift into and out of gear easily and the brake stops the tractor cold. With the engine running, once I start driving it in forward or reverse, it wants to keep going slowly in that direction even with the drive pedal released. The brake barely works and I cannot get it out of gear without turning off the engine.

Is there some adjustment that would remove some tension when the drive pedal is released so it won't move on its own AND be able to shift without turning off the engine?