Have you checked to make sure your elevator spring isn't disconnected and dangling in the tail?
Some people 'lose' those on purpose. It would probably be all the 'assist' your yoke would have needed to mask a poor bushing set up. It would also explain a 'looser' feel. Flies like crap is subjective, what do you mean by that?
You were probably anxious to get back in and go and were overly optimistic on your version of 'CIGAR', 'stir the pot' or whatever.... been there done that, probably weren't looking for those answers when you reached out for ideas.
Check behind the panel, and in the tail.
The #'s don't have much value as they are different instruments. Previous GPS speeds vs current would have helped verify that. You probably have enough time in that bird to recognize missing an approach speed by 15mph, that isn't a small amount. You said flies like crap, not 'lands like a streak of shit' is it really landing 15mph faster?
Good luck, as above, I bet it's an easy peasy, but necessary fix.
Take care, Rob
