Hi. I own a 1998 chevy blazer. About 2 weeks ago it started shifting itself into 4wd. I would be driving and I would notice something wasnt right and when I looked over the 4wd hi light was on. It seems like it only does it when I am moving at a slow speed between 0-35mph. It has done it a few times since. After it has done that and I put in back in 2wd but it feels like something is holding it back, and something is rubbing up front and causes some noise and vibration. It seems like you have to give it more gas to go up a hill and it doesnt roll as easy or freely as it used to. Can anyone help with this problem??