In order to build "muscle memory" consider doing FMQ with paper and pencil. Practicing stippling this way helps you to think your way out of tight corners. Think about using lined notebook paper to practice loops and circles to help develop consistant shapes and sizes.
When I FMQ, I set the speed adjustment to a medium speed and unplug my foot pedal. I start off the edge of the quilt sandwich and hit the on/off switch. In this way, the speed is always the same, and I only have to worry about moving my hands in a smooth, consistent motion. When I get ready to stop, I work my way back off the edge of the quilt sandwich before I stop.
Another thing I was taught was before I begin to FMQ on a real quilt, practice with pencil and paper for a few minutes, then warm up on a practice quilt sandwich. This helps the muscle memory to kick in.
Good luck and keep practicing.