You cannot manually adjust the timing on this engine like you could on older, distributor-equipped vehicles. Any attempt to do so will likely damage the engine or the PCM.
If you suspect a timing issue, you need to have a qualified mechanic diagnose the problem using a scan tool capable of reading the PCM data and checking for any trouble codes. The problem might be related to the crank or camshaft sensor, the ignition system, the PCM itself, or even something else entirely.