Hi there, sorry about the delay for the answer to your question, but I can definetely help.
These codes are caused by an excessive lean condition, in most cases this is as simple as a vacuum leak. Check all vacuum hoses for breaks, or becoming disconnected. the fact that you have a lean code for both banks points to this.
Another possible cause if no leaks is found, is your pcv valve, or mass air flow sensor. To properly diagnose, a scanner required to monitor fuel trims, along with barometric pressure are required. If no leaks found, let me know if you have a scanner capabile to do this.
Also you stated, is a 5.8 engine, in this year, only a 5.4, 4.6 and 4.2 litre is availible, so I recommend double checking engine size on emission sticker under hood as well.
Thanks! Should be a simple fix.