Where do you live ? Get the car to a Tuner and have them street tune the car and see what they can tell from the data logs.
Or can you data log and send info to a Tuner ?
174,000+ miles, 5/20/12 new ej257 short block, 8/20/11 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. Also CHECK YOUR OIL, these cars use it.