Page 37 of your DX-7 manual explains "Throttle Recovery".

When you set up your throttle trim, allow enough down throttle trim to kill the engine.
Then, when flying, holding down the throttle trim switch will run the throttle servo all the way closed.
When ready to restart your plane, click the throtttle trim up once, and the servo will be set to your idle position.
Basically, this is the operation they use for throttle cut.

Works for me.

EJ