Off the line bog

Lifters dont "pump up". They are either working and maintaining 0 lash, or they arent. Bleeding down is when the rpms and valve springs collapse the hyd part of the lifter against the oil pressure..Thus the engine loses power..That's valve float. Variable duration lifters will "pump up" when the rpm raises off idle. They are designed to make large cams more drivable and idle better. But std lifters dont. It's not a lifter problem. You've already found the problem.