Welcome to the forums. Your post reads like you meant to type that into a Google search because you haven't provided any other info. Miles? Last time the fuel filters were changed? Driving scenario when the CEL came on? Anything that might help us understand your truck's current condition?
A common cause and relatively easy fix, if only temporary, would be to pull and clean the MAP sensor. If it's plugged and unable to read the correct manifold pressure then it's not going to inject the right amount of fuel which is what can cause the P026D code to trip. If it's not a plugged MAP then give this TSB a read as that may be the next course of action to check/try.