Hang in there, nitro can be a bit frustrating sometimes. Ok, let's go back to the start.
Get a fully charged receiver and radio pack.
Radio on, receiver on (engine not running).
Remove air filter and look down at the carb opening.
At neutral the carb should be fully closed (except for a very slight opening for idle)**.
Squeeze trigger fully. The carb opening should open fully (should look like a perfect circle).
Release trigger to neutral. Position should return to **.
Fully brake and release. Position should return to **.
Do this a few times back and forth while looking down the carb hole in any sequence and as fast or slow as you want. This action should happen every time exactly as above.
If it isn't you need to realign your throttle linkage properly using the stoppers and spring so that the action is consistent. If it still isn't working maybe your servo arm is stripped. Check that too.
Fyi, At neutral the carb should never stay open on its own.
If all that is correct, then your radio settings are good.
Now close both LSN and HSN all the way in. Be careful you don't over tighten them.
Then turn them both out 2.5 turns.
Start engine.