my 72 plymouth duster has a mopar 360 magnum crate engine. I am having issues with the clutch pedal sticking to the floor. When I push it in it will be strong but then near the end it gets really light and will occasionally stick right to the floor and stay there until I tap it with the side of my foot then it snaps right up hard. but when it doesn't, it is super light then just before it grabs it pushes alot harder. The clutch is new. Please tell me whats wrong and how to fix it.