Other possibilities could be;
intake vacuum leak, (not as likely as exhaust leak)
With the mileage on the vehicle there are possiblities due to wear and tear.
I used to live in Maryland and emissions would give you a waiver after you spent $400 or more to try to fix the issue. See if there are similar waivers where you live as you have spent a good deal of money so far.
Thursday, July 14th, 2011 AT 7:27 PM