It’s going to be adjust test, adjust test. I would wire throttle wide open. Pull KD fully applied and remove KD slack. My guess is it will hit hard and probably early. Then let off pressure “more slack in KD” until you get it where you want it. If it doesn’t hit hard, then something else is wrong. You said shifts so you have pressure. Scratch this>KD shaft not engaged on valve, pan coming off. VB not drilled right, missing check valve etc.
