But even @ no load, reeving the motor in neutral?
This is why the ignition system needs to be "scope" out, so the problem can start to be narrowed down.
You are not asking them to fix the problem, just start to find out what areas are good so you can look elsewhere.
If you don't have the right equipment to check it out, theres not a thing wrong with finding a shop to give you a hand.
Either that or just change every darn part until-bingo-you get it
Thats the wrong way to repair your car, anybody can do that.