Don't think about what you're doing.Just do it.(like that's a whole lot of help:))
When I was learning picking simple melody lines,and it was such that I needed to strike a bass line at virtually the same instant that I made the chord change,pausing and "concentrating" made my picking hand get left behind.But funny enough,when I stopped trying too much,it worked.
It'a a bit like a mobile phone game:you'll never set a new record when you're actuallt trying;it happens when you're not even thinking about it,just playing the game.
Try to relax.