TAYLOR! THANKS MEN!
That Kext was the problem! I delete com.paceap.kext.pacesupport.snowleopard and premiere is stable as a rock.
being working for 10 days on huge huge projects, with lots of different camera formats, scrubbing fast forward and back and doing edits without a single crash, while on this same project I used to have at least 2 restarts per day.
Not sure what this PACE snowleopard does on el capitan but is not good for adobe apps.
Hope this help others with Mac Pro and nvidia GPUs
Cheers! thanks again