Your prob may be your Sidewinder is too close to the rx since Sidewinder is mounted on the same side. Take a piece of scap lexan or a plastic divider from a parts box and trim it and drill 2 holes so you can mount the Sidewinder in the middle rear of the chassis where the orig esc was mounted. My Sidewinder is mounted with the motor wires on the right side looking from the rear toward the front. Batt leads are on the left.

Feed motor wiring thru the shocktower/rear body mount. I zip tied the wiring in a couple of places to keep it bundled together. I've never had any glitches or probs, been trouble free.

I used that cap on my Emaxx, but that was to help lower EVX temps not solve glitching. It did drop temps, I was not having any glitching probs on that one either. It just plugged into an empty slot in the rx.