Are you doing the ice queen method with your condish??? basically you condish your hair upside down and then scrunch and squish it till it feels like seaweed. You wash out the condish with your head upside down. You will also put your product upside down. Then slowly turn your head over and put product in upright. That should definitley help with clumping. If you do a search and type in ice queen you shold be able to find the thread.
Also, not sure if mousse is a strong enough hold product. I could be wrong , though.