Freakin' out... Tranny/Engine Mount?

[stateofidleness]

Gents,
just got my top replaced!! so I'm all excited, and then I hear sounds that aren't normal and sound expensive. I first attributed the different sound of the car running to the new top (with glass), but it seems like the transmission "whine" in 1st and 2nd are more "low" pitch.. kinda like when you leave the vacuum in one spot for too long.

*This is a '00 base Tiptronic*

Car runs fine otherwise, but around 2000rpm (1800-2200 only, nowhere else) there is this "stutter" feel to the car if I accelerate slowly. It feels the same as when your transmission is slipping, but this is more of a noticeable vibration type feel.

The scary part happened today though when I got home. I pulled in to a spot, stopped, and then reversed to straighten out a bit. When I got done reversing, I put it back in Drive and it made this horrid noise like the engine banging against the firewall or something... fearing the worst, I thought to myself, "well... there it goes...". I immediately put it in Park, then back to Drive (almost assuming it wouldn't go into gear for some reason), but it went into gear just fine and I was able to park it.

I've been wanting to replace the engine mount for some time now as preventative maintenance (74k miles with no record of replacement), so I'm thinking it's either the mount is bad or something worse... the tran$mi$$ion. Could it be a misfire or something else even?