2000 Ranger Thumping

2000 Ranger XLT 4x4. I'm getting what sounds like a thumping or bumping noice while driving..forward or reverse. You can also feel it. It's louder when I turn either direction. Seems to lessen at higher speeds. I thought it might be a flat spot on tires, but eliminated that. Any ideas?
Also, I have been having a problem with the automatic lock outs. The 4 wheel engages fine, but unless I go in reverse first, it takes a long time for them to disengage. When switched to 2-wheel, I only get two wheel drive but the lock outs seem still engaged. When it releases, it's a loud thud or knock.
Can these be related?

Thanks