http://www.bayern-chemie.com/ramjet.htm
The rocket is the booster and the ramjet is the sustainer. Seems the weapon can throttle back to save energy for the end game, but not sure if it can shut down and restart the ramjet engine for long-range shots.
A restartable rocket motor was planned for one of the AAAM compeditors before that program got killed in the early 1990s. Pretty interesting stuff (if you're an engineer at least) but that is not something that Meteor uses. Python 5 can supposedly control how fast the fuel burns too, to prevent it from going too fast and overshooting when being fired over the shoulder.