I had a similar experience. Went from an older senate to the 2014? green vapor. I loved how fast the ski felt initially but it seemed "off". The ski seems pretty sensitive to fin settings. There are several lengthy threads on this forum regarding fin settings for that era vapor that I read multiple times...long/shallow, short/deep. Even though I prefer to set it and forget it, I spent the better part of a summer trying different settings.I experienced everything from ski not turning, to tail blowing out, to having the ski "hunting" when I rode it on a straight path. So frustrating. I finally happened upon a setting that works for me and I have been happy with it ever since. I started on that ski trying to consistently run -15, 34. Last weekend I got a practice PB. Slowed down to 33 and got around 5 ball at -32.
Be patient with the process.