I am wondering what my next logical step should be, am stumped on this one. 2.4L engine, 149,000 miles, runs fantastic, A/C. Overheats primarily on interstate, but sometimes during city driving. I have replaced thermostat, radiator cap, most of the hoses, coolant temperature sending unit; have flushed coolant system (the full 3 drain/flush/fill method) and added proper mix antifreeze, removed and cleaned resevoir tank, water pump is fine, no water leaks anywhere, powerwashed radiator fins to remove road grime buildup, both lo speed and hi speed coolant fans turn on at proper time and airflow is good (plus running 70mph on interstate should push large amount of air through radiator fins.
Should I remove thermostat altogether (live in Phoenix, don't need heater
), or replace radiator (not sure how to check for proper rate of water flow - possible rust/etc buildup?), or something besides these options?