I also had an ongoing problem with my solenoids. You can read about it all here
http://vehicross.info/forums/showthread.php?t=23124

Intermittent, hard to recreate, real pain in the *** annoying. Mine had a missed shift as well, which happened at a specific speed (ie, a shift point that it would miss). But I suspect that more than one of my solenoids was failing, as I had jerky downshifts too. Replaced them all and so far no issues.

That may or may not be the problem: check mounts as well.

But read through this, to see if any of it sounds familiar
http://vehicross.info/forums/showthread.php?t=23124