join the club of emi i did all that you have done and a lot more still i have the problem and a pcm or one with a failsafe is not gona make life easer i am putting a standard hitec in mine so i can see the interferance when running it is the most anoying thing to find i even tryied different tx it made a big change but not enough to want to fly it also look at your switch to battery as a lot with the vibration can cause a fault i tried direct to the reciever but it was not where my emi is i am still looking i am about to pay for a guy with a spectrom analiser to locate the problem . how far away is your battery and ing battery they should be at leeast 10 inch away from motor ant 5 inch from each other .
what is your spark plug gap .
has it got a sheilded spark plug cap . if not look at getting one .