Here are a couple of troubleshooting steps I'd do:

Have you plugged in a meter to your receiver to see if you're getting the right voltage all the time? It sounds odd that your ignition light goes off as you advance the throttle, but I've never used one so maybe that's normal. If you're getting a constant voltage reading, then you know your regulator is good.

Have you spoken to the manufacturer of your kill switch and your ignition to see if it's normal for the LED to go out when you advance the throttle?

As mentioned above, have you tried bypassing the ignition stuff and running your receiver straight off the regulator? That will show you if the receiver or servo is the problem.