brushless problems

[rcsammy]

Hi everyone, ive been having some problems with my brushless setup in my rustler and i dont know where else to ask as i cant figure it out

after rebuilding it the other day the power seems to pulse, it effects the motor, the cooling fan and the steering
i have changed the motor, battery and receiver to try and work out whats causing it which narrows it down to the ESC or the BEC

im running a Mamba Max with an external BEC(dont know the make) i dont have another ESC or BEC to test it
i have tried plugging the MM in without the BEC but it just does nothing, i have no idea why

heres a video(apoligies for rubbish quality) hopefully it shows the problem a bit more
http://www.youtube.com/watch?v=kOBhbBriwqU