I had a similar problem at the start of the year. Mine wasn't quite as bad, it didn't make the car cut out, but it glitched BADLY all the time. I too changed everything.
Eventually I got some new LiPo's and hey presto, problem solved. I tried the old ones and they didn't work so got mega stressed, and threw them at the floor when they wouldn't charge.....
.....My brother now uses the old pack without a problem!!
There was something obviously not connecting right in the pack, and when it had the jolt as it hit the floor, it must have knocked something back into place!
...not that I'm telling you to throw your LiPo's around, as its not a good idea really....a moment of madness. lol