'07 V8 P0171 P0172 P0174 P0175 codes
 

What I have tried to get these codes to go away: Replaced MAF, Smoke tested, put some RTV around the crappy gasket between the Throttle body and the Intake while I completely cleaned the Throttle body, inspected all vacuum lines and all the intake hoses.

all these codes pop up at once and then will go away for a day, then pop back up, all the same codes, hang around a couple of days, then all will go away.

It is definitely intermittent.

Any ideas?

You are flopping between lean and rich, this can mean bad O2 sensors but typically you end up with just one bank throwing a code at first. If both banks act the same way, its likely up stream. Check for exhaust leaks at manifolds (those bolts loosen up). Check the EGR interface to exhaust, make sure those bolts also did not back out. You also may want to check out the MAP sensor. Another thing I have seen a couple times now is a cracked intake tube downstream of the MAF so maybe check for that too. Usually right where the MAF resonator and flexible intake tube meet.

That MAP sensor looks like it is NO fun to get to. How much of a possibility is it that it may be the culprit?

Its not terrible, but its certainly not fun. The electrical connector is the worst bit, I broke mine without knowing until I went to plug it back in. Was not even rough with it. A thread on my fun:

https://landroverforums.com/forum/lr...nnector-94531/

When a MAP sensor goes bad, vacuum is not measures right (aka, engine load) so the engine tends to go between lean/rich as it tries to compensate. But honestly a bad MAP is a guess with no code flat out saying its bad. Have you ever replaced the PCV valve? I wonder if it could be the issue. The thing it from what I have read, when they fail they fail open causing a big vacuum leak and horrible performance. So one sorta knows when they go bad.