My boyfriend happens to have his own mechanical/autobody shop so I get a special rate. The short trips are a commute to work-about a 20 min dive one way on hwy. I had the 2 front 02 sensors tested as someone had sugggested here and they were very bad so i replaced them but now the CEL came on this morning and has now since gone off again. It seemed to do this last time and then it came on again a day or so later that's when it came up with the o2 sensor codes. Im still not getting the mileage it should be so i have to wait for the CEL to come on to read the codes. Im guessing it is the back two now. It seems to be my luck with this truck lately. Dont know what else it can be. Just for reference 02 sensors in Canada range from $80.00 each for aftermarket and 175.00 each for OEM. Thanks for the input.