Interesting. Mine was doing the same thing a month ago. But I get it every once a while. Then I got BFG MT and now all I feel is the rumble from the tires. But every once a while I think it is that same issue.

So, you say to look at the Driver side Motor mounts. I'll have to check that out.

Editted:
Where do I actually look at? Is it in the hood below the Air Box. Man I need to clean out my engine.