I always ran Mobil 93, but they left my area so I switched to Sunoco 94 and didn't notice any difference besides a thinner wallet. This week, I tried Shell V-Power 93 and the car seems to really like it... that or it's placebo.
WRT to the stuttering, I guess I'm lucky that I have an early build and the stuttering seems to have stopped since I passed ~3k miles.
I hope those stuttering and bucking get it sorted out soon.