Trouble code p0191

[budweiser.junky]

Hello everyone new member and new to buick enclave. So last year i purchased a used 2009 buick enclave cxl for my wife and i must say i have been very satisfied. However now i have an issue that is seriously bothering me, mil light came on and i started getting low gas mileage and loss of performance when accelerating and at low rpm. Fuel pump had a very loud whine. Scanned and i got p0191, p0161, and p069e with all seem to point to fuel delivery. Being the pump was loud i bought new one and switched out however problem persisted. So next i got the fuel rail pressure sensor, replaced and what do you know performance issues went away however after a day of drive mil came back on and it is giving me same code. Checked for cracked or bare wires and as far as i can trace they are in good condition. Any ideas as to what could be causing this code to continue to linger around? Any and all help would be greatly appreciated.

 

[HotZ28]

There may be some more ideas on things to do & check in this link: https://www.obd-codes.com/p0191

 

[budweiser.junky]

Thanks for the link, very helpful however problem still persists. I did come across something about engine mount vacuum for ride stability. Does anyone know how to tell if my vehicle is equipped with it. I have a CXL with pretty much every option except navigation. I heard that if its not equipped that there is a nipple somewhere on intake manifold that has rubber cap and it gets knocked off when changing spark plugs, however I cannot seem to find it.