Buy Michael Packer's DVD and study/practice the techniques and patterns he teaches.
Aside from this Always practice with a metronome. Start at around 35 BPM and play quarter notes (1, 2, 3, 4...) and eigth notes (1&, 2&, 3&, 4&...). Once you have mastered these consistantly for say 10mins. Then do triplets (1&a, 2&a, 3&a, 4&a...) then quads/sixteenths (1e&a, 2e&a, 3e&a, 4e&a...).
After you have mastered these while playing eights on the hi-hat ans 2 & 4 on the snare then start mixing the up in grooves. Always with the metronome. I recommend counting them out loud as you do them. If you cannot play them consistantly for 5-10 mins no mistakes do not speed up until you can.
Muscle fatigue causes mistakes. This method builds you r muscle control, muscle memory and muscle endurance. You have to play grooves on record for 3-5 mins this will get you there.