First thing always when you have a weird transmission problem is to put a set of gauges on it. Especially a Mopar transmission. The engineers were actually nice to you a pressure port for every friction element. Valvebody controls the fluid flow so if it has pressure where it is not supposed to be a valvebody issue, if it has pressure where it is supposed to be then a mechanical issue with the band or clutch pack. Plus with the valve body off you you can air check all the clutches and bands as well and listen for any leakage past sealing rings.