P0174 P0171 Codes Showing on my 2005 55 Jaguar XK150 32K miles

Bought myself a little OBII Bluetooth code reader the other day, only to find that there are codes for the engine running too lean,

I cant say I've ever noticed the XK misbehaving in any way, although I have found that after a good while of driving, when the car comes to a stop, the revs slightly dip and then comes back up again, its not entirely noticeable but I have read about it happening with these codes, Not really sure if this is related but I will add that If you rev the car slightly whilst stationary and letting it rest again, I've found on a really rare occasion that the car starts climbing revs to around 3.5k and then very slowly coming back down to what it should be again without touching any pedals.

Ive read the live data on the torque (lite) app and I seriously don't understand whats wrong here, both bank 1 sensor 2 and bank 2 sensor 2 show the same numbers from the start of a drive to finish -1.6 is what they read, I use a Dial and it tells me max and min using arrow indicators evolving around the circle, also if you are wondering why I'm using sensors 2 on bank 1 and bank 2, that is because that's the only ones displaying data, not sure why this is,

I'm going to have a look at the 02 sensors on bank 1 and 2 the next time I'm out a drive, I've been told that it should fluctuate between 0-1 volts,

If anyone has had these issues, please let me know,

Ill try to post updates as I go along finding things, I'm going to remove the engine cover and start checking for vacuum lines, maybe clean out the MAF sensor, knowing my luck though I wont be able to find the issue and need to take the XK to a garage,

Ive only just bought the car a few months ago, I was planning to give the car a Major service for piece of mind, MOT due up on October 29th, so would be planning on servicing it at the same time,

Kind regards,