2006 Range Rover HSE 240k miles 4.4 liter v8.

Truck runs well- It would always get a p0442 (slight evap leak code) (new gas cap did not fix), since I've had the truck at 206k miles. I would clear the code each year before inspection to pass.

This year the truck got a p0171 in addition to the p0442 code.

I am aware of what can cause the p0171 code:

Fuel pressure
Vacuum leaks
MAF (Usually accompanied by a p0174)
Dirty fuel injectors
Bad PCV valve.

When I first got the code I replaced the pcv valve as this fixed my 04 xj8 with the same engine and same code. This did not fix the Rover. Actually after a day of my wife driving it (her car) it started a smoke show that filled the street, swapping to the old pcv fixed this issue. I put the pcv that was working fine on the jag on the Rover (same part) and the smoke show ensued shortly after driving. I installed a inline catch can on the rover, no smoke show but took it off as that's what I have installed on the jag - so that baffles me. I put the 'old rover' pcv on the jag for 2 days, car ran fine no smoke no engine codes etc, leads me to believe the pcv valve is ok.

I cleaned the maf and drove the truck for a week - no code but the inspection place kept saying it was giving a non ready evap and o2 sensors. Then the code hit again. p0171 and p0442

I am not afraid of doing work myself I've rebuild several engines, transmissions, cars, etc. I didn't want to throw parts at it. People said the Rover techs can read more into what the car is saying than my typical scanner..or update the fuel trims and engine software to make it not code so easily?... so I brought it to a well reviewed Rover tech in my area (raleigh nc).

They immediately said p0171 is a maf issue. I said ok this makes some sense as cleaning the maf helped. Also they agreed they reset the adaptations when the truck gets a new maf so I was glad to have them do this simple procedure.

Well they call me today - issue has come back. p0171. Guy said he smoke tested it no vacuum leaks etc. I mentioned that it may be the pcv valve and mentioned the smoking thing to him and he stated he had never seen that before. Says the engine software is up to date.

I'm thinking to myself jesus I can throw parts on the damn truck if that is all they are going to do - for the price of they charged for the maf I could have had the injectors rebuilt, put it new o2 sensors etc. I dont want to pay for a part they said would fix and didnt especially since it takes 2 minutes to remove.

At this point in time the shop said they are looking further into it and not going to charge me, I confirmed this with them and they said no we are not that kind of shop.

That being said who has actually resolved this issue? People post about it then rarely post the resolution. Truck has good power and is not missing with this code. Also despite the pcv smoking thing it didn't have oil consumption that was noticeable between 3k mile oil changes.

My next step before I decided to take it to the shop was to swap the o2 sensors, move the driver's to the passenger, passenger to the drivers to see if the code follows.

Also I was going to throw the catch can back on with the good pcv and see what happens.

Thoughts?

Is their a sort of fuel pressure regulator for the passenger bank only?

Thank you!