Did you clear the trouble code with a scanner after replacing the CTS? If you didn't; the problem often will continue until the code is cleared.
On the 4 cylinder engine; I would replace the spark plugs with only Champion #7348 (KC11PYP) and also replace the fuel filter, inspect the air filter and replace it if light does not easily pass through the element; thoroughly clean the mass airflow sensor and throttle body, and replace the intake air temperature sensor.
If the problem continues; I would replace the ignition coil assembly, which is a known problem area on this model. Airtex/Wells manufactures an improved replacement coil assembly for the 2.3 liter 4 cylinder motor; under their part #5C1762.