My 2000 GMC Sierra 3/4 ton 4x4 was getting getting about 13mpg (not good to start with) when it suddenly dropped to 8mpg. Plugs, air filter and O2 sensor have all been changed out to no avail. Any ideas on other avenues to investigate? This is a farm truck that has to be used; help!
Apr 15, 2010 at 6:11 PM