Help with Midi Device

I'm new to MaxForLive, old to programming, but I'm struggling a bit to come up with a solution for a need. I have an instrument, a Chapman Stick that has a GK3 going into a Roland VG-99. the midi out is terrible, possibly because of the way the instrument is played. So I had an idea and wonder if someone could help me with a few tips or pointers.
When I play a note, because i am tapping the strings, when I let off or even when I play the pitch changes a lot. Really bad when I let off the note. I've been able to compensate with one soft sampler but most sound terrible.
So I am wondering if I can take the midi signal and round and hold to a note, and also cut off the note when the velocity falls below a certain level. So it just kind of triggers notes by rounding the pitch mostly up and holds until velocity falls below a setting. The issue while playing the Stick usually has the note dropping in pitch as I release the note and it sounds terrible on most soft synths.
Any help would be greatly appreciated.

MD