Sorry this is all late, I ended up getting the Summit Racing brand. They're just like Pacesetter, but without the fancy stickers and high price.

 

Do you have a breather on the pass side valve cover instead of a cap? P0171 is unmetered air. Remove breather or replace cap, reset code. I've had this issue on my Lightning and almost everyone with a breather has had it aswell.

 

its really stupid but have you checked the airfilter for clogs, wet spots, etc. it can set that dam code off too.

 

yes I've replaced just about damn near everything associated with these codes. Everything but the intake gaskets