When if shift into 4x4 it feels like the brakes are pulling and there is rough sound from the back. When i shift back into 2WD it will not shift back right away, only when i turn the jeep off and wait 1 min will it shift back. Also my selec-trac has a hard time moving below 4wd Nutral, i have to pull with both hands very hard to move it. Any clues? I own a 2002 Jeep Grand Chorekee (50k)