I have a problem with my clutch, its for a 2003 F-150 2wd standard transmission with a 4.2L efi V6, and i'm not sure what i need to replace. It feels really mushy from the resting point to the friction point. It also will not shift into gear while the car is on. The clutch will hold the truck by itself on a hill and it will stall if I pull it our too fast in 1st or 2nd gear. I'm curious to know the effects of a bad master cylinder. (The clutch was replaced 100,000 miles ago.)