If you didn't change the CPS yourself, check around the throttle body for leaks, this would include the hoses for the PCV system. Then put a fuel pressure gauge on the fuel rail and check that. Should be about 56 psi running. Also re-torque your manifold bolts and check the 4 clamps at the back of the engine, these are known to leak air also.

Air leaks and/or low fuel pressure can cause a lean missfire.