Have you checked for vacuum leaks?
Spraying carb clean around the engine while it is running can show leaks by way of idle increase (the carb clean is sucked-in where the leak is and the engine rpm's increase).
I don't like using carb clean as it is flammable.
I prefer a smoke machine:
http://www.youtube.com/watch?v=-V_W_SFxYoI
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