had lots of problems yesterday racing

my get 2 RX8/tekin 1900 motor in 1/8 ebuggy was cogging/turning off all throughout my runs! I replaced sensor wire, that wasn't it
I'm thinking its either sensor board on motor OR esc connection between the boards
I had throttle then none then back on every couple seconds
sometimes It would lose steering also and transponder was not being picked up every lap
ALSO, If you pull gas trigger nothing happens, IF you push it and pull gas while rolling motor gets power

any help?
thanks