THIS PROBLEM STARTED OVER 2 YEARS AGO; HAVE HAD 3 MECHANICS CHECK IT; CHANGED FUEL FILTERS; REPLACED FUEL PUMP LATE 2008; REBUILT TRANSMISSION IN DEC. 2011; SENSOR WAS CHANGED. MASS AIRFLOW SENSOR WAS CHECKED; IT IS OKAY. IS GETTING WORSE ESPECIALLY WITH OUR HUMIDITY AND LAST WEEK IT WOULD HARDLY RUN IN MISSOURI AROUND TOWN; OUT ON THE ROAD IT IS FINE. CHECK ENGINE LIGHT IS ON; MECHANICS CHECK IT AND CANNOT FIND ANYTHING!! LOVE THE OLD TRUCK; 173,000 MILES; HATE TO GIVE IT UP BUT FEEL IT IS NOT DEPENDABLE NOW!! HELP!!