to me it sounds like the esc is overloaded.Or getting spiked by HUGE amp draw.Is it the stock esc and motor?I have the stock esc and had the same problem when I ran a 21tdouble motor that was geared too high.I went down to a smaller pinion and all was good. I know that the esc is rated only for 23t motors,but I have run this setup for 6 months no problems.