code 172 system lean on 95 contour 2.0

starting the car up seems to have no issues, but when driving CEL comes on and gives the code 172, changed PCV valve and grommet, grommet was worn out, still get the same code, replaced MAF sensor and sprayed connections but still no leaks detected, was getting a code 335 KOEO and 336 KOER, changed the DPFE and the 336 is no longer present but still getting the 336 KOEO and code 172, did fuel pressure check and I get 30 psi at idle and 40 psi with the regulator vacuum line disconnected, is 30psi normal or should it be higher, any help would be greatly appreciated