My Yukon gets horrible fuel mileage, around 12-14mpg. Anything I can check or do to help with this?? It has a newer engine in it, installed by dealer due to lifter issue. About 130,000 miles on the engine and 228,000 miles on the vehicle. Thanks

12-14MPG city and/or highway and/or on the drag strip and/or . . . ?

Is the check engine light on?

Lots of idle time?

What region are you in?

Aftermarket tires and/or wheels?

2WD or 4WD?

Driving alone and/or with lots of passengers and/or loaded cargo area and/or towing and/or cargo on top?

Does it get regular maintenance?

Does it have a giant cow-catching push-bumper?

How many miles have you owned it?

Has it had the spark plugs replaced since the new engine was installed?

112,121 miles when I bought it. 4wheel drive. Stock wheels, tires and stock bumper. Some in town driving but mostly highway.
Ive changed plugs and wires and I keep up on maintenance pretty well. Change oil every 4-5 thousand miles.

I live in montana. Very seldom is it used to tow anything. Only thing it hauls is 3 kids

Is the check engine light on?

Lots of idle time?

How many miles since the spark plugs have been replaced?

Is AFM still enabled?

. . . and where are you getting your MPG data?