Bad MPG and Oil consumption

Some Background:
My truck now has about 102k miles on it. I change my oil and rotate tires about every 5k miles. I use Mobile 1 full synthetic. I did my 90k mile maintenance, which included plugs, filters, and all the oils. I also replaced the break fluid and some of the coolant.

I noticed last oil change that my truck had started to consume oil. I was about a quart low when I changed it at 5k miles. I don't normally keep track of my mileage, and I have two cars so it was hard for me to tell when the truck was using to much gas. However, on my recent road trip to the midwest this last week, it was easy to notice. I was running about 14 mpg. This was very low and if I would guess I would think both problems happened at the same time.

Anyone have any insight that may help me diagnose and fix the problem?

 

I would start with a compression check.

 

This. You can learn many things about you motor with a compression test.