Hey Ronnie -

I would suggest going through the core lessons from the very beginning. At first you will find it easy and fly through, but you'll hit a point where it's new. From there, you can slow down and focus.

I was exactly in your position playing with a church group. I could play competently, but I found it really hard to keep up with the chord changes and keep the rhythm with the group. The good news for you is that this situation gives you the perfect opportunity to improve tremendously in this area.

What I did was I recorded our practice sessions. I would then spend hours playing along with my recording fine tuning my strumming and chord changes. With the way things are today, you can even slow the music down without changing the key to help you get it down.

Also, whenever you are practicing - whether it's "noodling" around or playing through songs, use a drum beat or a meternome. This will help you keep in time.

Best of luck! Ask questions here if you need to.