I would see if you have a vacuum leak at the intake manifold. Luigisho posted how to check that. The clamps should be loose to allow the intake manifold to move a little when you are reinstalling it, then you tighten them down.
When you installed the timing belt, there are four locations to check the belt is aligned correctly. The SHO engine book shows those locations, did you align those?
There is a way to test the CPS to see if its good before you replace it. There are previous threads in this forum.