My sliding rear window does not work anymore
My 4x4 engages maybe 50% of the time
truck is an '05 lariat screw with 43,000 miles

 

I wish I could be of more help other than to tell you to check the connections and fuses - maybe take a multimeter to the wires and make sure it's not the switch itself that is bad.

 

I would definitely go check the battery connections, especially the ground cable, and the positive pole for corrosion. Frequently these kind of gremlins are caused by a high level of resistance being present. Also try going to a parts store and getting a free battery test-they aren't as goos as a load test like a mechanic can do but they are worth the price (free).