low mpg

I've got a 96 single cab 2.7L 4x4 and only getting 13 mpg in town. Is there something wrong? My catalytic converter is rattling so would that affect the o2 sensor and affect the mpg. There is also a check engine light on but we bought it wrecked so we just thought it was from the wreck, it runs good though. I know it needs a new catalytic converter, so which one/brand should I buy? It really needs a new muffler too.

 

I have the same engine and i was getting horrible mpg with my check engine light on. It was the O2 sensors, once i replaced them It was much better.

Go to oriellys or a place that can scan your check engine light for you. If the O2 sensors are bad, first take them out and clean them. If that doesnt work then youll have to replace it. The front/upstream sensor is like 200 bucks, but the rear/down stream sensor is like 80

 

Could the catalytic converter being junk affect the sensors by it.

 

Id assume so. If you know the cat is bad then replace that first. If its a low mileage car then the sensors should be good.

 

Its got 155000