Bad MPG

[Bhintz]

I have a 00 Z71 I got in the summer, when I got it i was getting 15/16 city/hw now is 12/14 I changed plugs, wires, air filter, and even put a new exhaust (flowmaster) and nothing no change is there anything else I can do

 

[sled_dog]

no service engine soon light? My 97 has gotten crappy mileage most of the time I've had it. It has 2 bad O2 sesnors.

 

[Bhintz]

nope no light I was thinking it could be the o2 sensors