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.
188k, 5/20/12 new ej257 short block, 8/20/11 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. CHECK your oil, these cars use it.
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