High Pressure Fuel Pump Problems

[Brian17]

I have a 2010 Equinox 3.0 with 88,000 miles. Two injectors went bad and aftermarket O2 sensors were not reading proper voltage. It has never idled right after these repairs and still doesn't. It would idle around 500 and erratically. I replaced both pcv valves trying to fix this issue. After the pcv valves were changed P0171 and P0174 came back. Since then the CEL has continued to come on sporadically with these codes only. It continues to idle around 500, sometimes steady and sometimes it jumps around. Long story short it now has all new injectors, new air box and new MAF. I have smoked the intake twice and found nothing. I was told the high pressure fuel pump is bad because at idle it is only registering mid 200 to 300 psi on the scanner. What are the ranges for fuel pressure on this vehicle? Does anyone have any other ideas or is it the HPFP?