Did you notice the rumble even on decleration - I've notice that it happens both accelerating and when you take your foot off the gas....but still while you are in the 30MPH-45MPH range...
I have an 03...I'll likely have a mechanic do it, just to avoid the hassle - I'm going to be pulling a boat this summer, so want to get it taken care of.
I did a drive with a mechanic and he seemed to think it was staying in 4th gear too long. Are you still having luck with the fluid swap? I'm going to give the lower gear a try too - I did that once and thought I felt it - but could have just been a fluke.
Flutter at 30-40
Hi - i have an 03 4WD and recently started noticing the same thing - I actually did think i was hitting the speed ripples the first few times it happened. Did you have any luck figuring out what was going on?