I just had a thought. Try dotted-rhythm position-clusters.
In case you don't know what they are, here's a brief explanation:
Play C-D-E simultaneously with 1-2-3. Hold this cluster while mentally preparing for playing the next cluster (F-G-A-B with 1-2-3-4). then make a quick jump to the 1-2-3-4 cluster. Do this over the entire range that you plan to play the scale on.
Then try playing the scale using different rhythms. Accent on every 2nd note, every 3rd note, every 4th note, every 8th note, etc.
if you need more help, don't hesitate to ask.