Hi Doug
I teach and sell Roland Atelier home organs for a living. They're kind of like arranger keyboards in a cabinet.
I'd be interested to hear any specific problems that you may be encountering.
In the meantime, make sure you practice more than exercises. Music should be fun, so play some songs that you like. When you play tunes for fun, thow out all the theory and and just play. If you make a mistake, I can tell you the best thing you can do is to learn to laugh about it. This will keep you more relaxed and up. If you do that you continue having fun and remain more relaxed while you get better through repititon.
Also, the biggest secret to playing is to hear the melody in your head, or even to sing along. This works whether you are reading music or playing by ear. If you can hear or sing it, you can play it.
My guess is that you need to stop using the logical part of your brain. This is the part that analyzes everything. It is the part of your brain that balances the checkbook. In the early stages of learning a song, you might need to figure out what finger on what note. Once you've done that, go for it, remembering to hear the melody in your head. Your fingers tend to go where you are thinking/hearing. If a person continues to think what finger on what note, this is when it is more difficult, tends to sound unmusical and really is no fun.
Let me know what you are experienceing and I will give you some tips that I see helps my students overcome the common pitfalls every day.
Best
Scott