HELP! Looking at buying a used 2014 GT, but car has sluggish performance below 3200 RPM (great above 3200) and dealer had trouble getting it pass emissions (finally did). Car has Roush exhaust and I don't know if it has been tuned. Could this just be running 87 if the car is tuned to 93? Or potentially a bad/non existent tune after exhaust was added? Dealer tells me that no codes are being thrown. Just trying to make decision on the purchase and looking for advise from some experts; take the chance that it is just needs a correct tune and hope that no damage has been done (not sure how long the car has been running this way) or run for the hills to look for a lower risk car?

Thanks Stang fans!