Have you checked fuel pressure yet?
When you installed the new FP did you make sure the O ring did not "fold up" on you.
This happened to me.
It was not lean after it was installed but become lean after I did a few WOT passes while adjusting my boost controller.
In any case, check your fuel pressure first before going on to anything else.
At idle with the vacuum hose connected to the FPR you should get about 34 psi and without vacuum you should get 43-45 psi.