I have a 2003 Expedition 4WD. Shifting into 4 hi has become problematic. I can do it from a stand still....most of the time. Sometimes it takes a little moving the switch back and forth a couple of times to get the light to come on in the control cluster. I can shift on the fly, but it drops into 4 hi like a ton of bricks, makes a loud bang and the speed drops way off instantly. Anybody had a similar problem? Where do you all reckon I should start? Thanks!