I know it's been a while, but I just wanted to post an update on my situation in case anyone else has the same problem:

My car magically got better over time, just like Max's did.
It drives fine - the only issue is that when I first start the car, it idles at about 1200 RPM until I get moving (I don't think it used to idle that high at first).
I also had Eurocharged retune my car and now I'm enjoying the improved response.

Again, thanks everyone for all the suggestions along the way.