Remember, the truck does not diagnosis itself.
Those codes are merely clues at what the scanner see's
The kid at the parts counter probably doesn't really know either (otherwise he would be working as a high paid technician rather than a clerk) but he will be happy to wheel out the parts canon and help you spend money.
Goggle those codes and post what YOU think is going on here and I will (or others) will suggest how to test and prove your theory BEFORE you start to replace parts.
I hope this helps you.
Please return and tell how this information worked for you, what you find, and how you eventually fix your vehicle (even if it is that you brought it to a mechanic / dealership for repair)
It is your feedback and final repair report that will make these forums useful to others in the future.
Many times I search and find the same exact fault that I am having, someone suggests how to fix it, the patron follows the suggestion and then never returns to say YEA! or NAY...
The forum thread just goes dead because the person fixed their fault and has not a care to offer the answer anymore. Please don't be that guy.
Cheers!