It sounds to me like you are lacking in the stick control area and are letting the rebound do most of the work for you. What you need to work on with the left hand (and the right while you are at it) is to practice stopping the stick at the tacet height right after an accent. If you can control the stopping of the stick when it has a lot of momentum, it will allow you to change it's direction to execute a good grace note.
The easiest way to break down technique issues is to isolate each movement.
To work on it, try this exercise (Initially, don't try to keep any sort of tempo, just leave plenty of room in between each rep so that you are physically stopping the stick for a second or two.):
Play isolated legato accents.
Now let's try stopping the stick: The instant the stick starts to come back up, start the movement to bring it back down again (almost as if you were trying to play a diddle.) As your hand movement takes the energy out of the rebound, try to freeze the stick into tacet position (there will be some wobble up and down when you first try this and that's OK. The more you practice it, the less wobble you will have.) Wait a second with the stick frozen in the tacet position and then repeat.
Once you are able to stop the stick while it's on it's way back up, then try adding the grace note attack after the pause. Place the grace note tap, don't just drop it in. As you get used to that movement, gradually make the duration of the pause a little bit shorter in tiny increments (make sure you play it correctly before you try to shorten the pause again.) Eventually, you will get to the point where you are leaving no extended pause in between the attacks.
Now try playing the alternating flams, but at a slow tempo. Then you can build the speed.
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The Cavaliers - Baritone 1993
Hawthorne Caballeros - Baritone 1988, Contra 1989-1995, Bass 6/5 1996-1998
Pequannock HS - Marching Instructor 1995
Saddle Brook HS - Percussion Instructor 1995
Lodi HS - Percussion Instructor 1996-2003