I feel a positive shift from 2h to 4h, but the lever will easily move left and right while in the low position. I can't even find N let alone 4L. Am I even in 4h?
There are two shift arms on the transfer case. Linkage goes from the shift lever to both. One engages the front drive shaft (2wd vs 4wd). The other shifts the transfer gear from high to neutral to low. As mace said, it's probably something wring with the transfer gear linkage. You can see the linkages from under the truck on the passenger side of the transfer case.