I have a right hand drive 1998 jeep Cherokee for delivering mail. In the past few days after I have been out on the route for about an hour my jeep starts to idle rough, odor from exhaust also. Seems to be burning more gas than usual. Check engine light came on and I took it to Auto Zone for check, not sure what the code # was but they said fuel pump. Not sure if this is correct. Seems like it would not be using more gas if it was the fuel pump. After I finish my route and drive home it seems to run better and it does ok in the morning. Any thoughts?