I have a 98 4x4 3500 Silverado that feels stuck in 4 wheel drive. Have recently replaced electric actuator because I had no 4 wheel drive at all. Now I have 4 wheel drive but even when stick shifter is in 2H position the front feels sluggish and has low humming tone to it. With all wheels off ground 4 wheel works in both H and L. When shifted to 2H all wheels still rotate but front wheels easy to stop by hand and hold still but has slight rotational pull to it. I can get fronts to stop turning if I put transmission and transfer case both in neutral then first shift transfer case into 2H then, of course, shift transmission into D. Truck will spontaneously drop into this sluggish 4 wheel drive situation with the tone. Any ideas are appreciated.