Either wait for the CEL
Or take it to a local mechanic.
I wonder if replacing the O2 sensor's may be the next step.
Hate to throw money at it without knowing what's going to fix it.
224,000miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. CHECK your oil, these cars use it.
Engine Build - Click Here