Dene 
2002 Toyota Highlander SUV 2WD 4dr SUV (2.4L 4cyl 4A)
Problem Solved Early
 After owning the car a few years, my check engine light would come on and go off.  The service manager recommended that I do the cat. converter because it seemed that it was going out and I only had about 15,000 miles before my warranty was up.  I think this is problem with some of the Highlanders. And yes, the heater/air is acting up. 