I’ve had two customers come in with the same complaint that hated there diaphragm clutches. I changed them both to the OEM Borge and Beck design and they left smooth happy. I won’t install a diaphragm in any car I work on. Some people like them but I don’t. The ratio of the clutch release for a mopar is too fast for a diaphragm. Sounds like he’s got several problems envolved here.