I just started using airbrush, and now it doesn't spray color anymore

I thought it's clogged (I only used water to clean after using tamiya acrylics) so I soaked the parts in thinner... then it sparyed a little while, but now its not working again. I'm using propellant, after a while it gets really weak... So what is the problem? Spray with thinner after painting and soak the parts in thinner?