"I don't know anything about your fit other than the 110 stem (which Aaron is right, 110 would have meant that frame was way too big for you 20 years ago as we all had 120-130s), but from experience I might guess that part of the liveliness you feel in that bike is because of it's relatively small size compared to the others you're riding. A more compact frame can have different stiffness/damping characteristics that make it feel 'livelier' than a larger one, but even moreso, I'm a strong believer in the mental aspect of the small bike. My personal opinion is that your brain likes the look of a smaller bike under you, makes you feel big and strong. When i was racing in Europe many years ago, it was common for riders to talk about good days and bad days in terms like 'I had long legs today' or 'felt like I could crush my bicycle beneath me' while bad days were days where 'I couldn't get on top of my bike today', 'too much bike under me', 'short legs today' etc.. Combine that with the improved straight line stability you feel with a longer stem (it takes larger inputs to achieve similar steering angles) and your brain is happy.