What radio/receiver are you using? I've had brown out issues in the past with my M8 & M11 Spektrum setups in my on-road cars. I've got both the Racers Edge and Spektrum brand glitch buster capacitors, just to see if there was a difference between brands, and my brown out issues have never been a problem since.

I've never experienced a glitching/brown out problem until I had upgraded my setups to digital servos...I'm not saying that's exactly what's causing your issues, just sharing my thoughts.

But give a glitch buster a shot if you have an open receiver slot. It doesn't have to be the most expensive one out there...you could even make your own if you have the necessary bits.

good luck