[CT_Nismo]

I used Nissan OEM gaskets and I am pretty sure they are in place. If there is a vacuum leak shouldn't I get an error code?

Yes you should be getting some error codes. But your LT fuel trim is way too high.

The definitive method to detect leaks is the smoke test. Not too expensive. But only mechanics have the equipment.

It could be an upstream O2 sensor. If you have the time, I would swap bank 1 for bank 2 and see if the problem moves with the change.

 

[CT_Nismo]

It seems to me

Before I start changing parts can someone please take a look at the following attached files and check if it is possible to figure out what is going on with my truck? I look at some data and realized the actual mpg is about 13. After driving 30miles LTFT went up. On the first report it was 10.16 on both sides and after driving about 30miles it went to 14.84/11.72.

OBD2_1.pdf - this is a diagnostic report generated on 9/17
OBD_2.pdf - second diagnostic report generated on 9/19 after driving about 30miles since 9/17.
OS_1.png - Oxygen sensor graph that i found on the OBD2 scanning software and not sure what it means.
OS_2.png - this is the voltage/time graph of the upstream Oxygen sensors. Orange line is bank 1 and Purple one is bank 2 (for some reason it shows up as sensor 5)
PID_Stats.png - Some stats that was able to capture when the vehicle was idling

It seems to me that your intake air temperature is way too high and all over the map. The ECM uses air temperature to compute molar (amount counted as discrete molecules) O2 flowrate. An error here will cause fuel trims to be high. I think the air flow temperature sensor is a combined unit with the MAF.

 

[CT_Nismo]

Got 98-100 while driving and when I stopped the vehicle it goes to 140.

I seriously doubt the 140 °F reading for idle. There is just not enough room between the air entrance and the MAF to heat the air by 40 °F. The MAF is a hot wire anemometer. The HWA has very tiny wires that are heated. I doubt said heating is enough to affect the air temperature.

With the truck at hiway speeds, I would put the tranny in neutral and take the foot off the gas. See how the inlet air temperature reacts. There should be little or no change.

 

[CT_Nismo]

One more thing that don't think was mentioned is the air filter. As it gets more restricted, you have to open the throttle slight more for the same power so now the TPS signal is causing the ECM to inject less fuel than the imbedded program would expect because it does not know the condition of the air filter.

The MAF also measures absolute pressure of the incoming air. This accounts for the increase pressure drop across the air filter as the contaminants accumulate. I think the variation in atmospheric pressure day by day is larger than any change due to the air filter.