Sorry about my post... I copied and pasted, and forgot to change the cylinder #s! I just edited my post to reflect corrections. So anyway, yes, that is what I was thinking. Will look into: 1.-- possible manifold leak, and 2. -- bad/open #6 injector. I feel like I am just throwing darts, but we will see.
Much thanks!

 

If both P0171 and P0174 are present, check for vacuum leak(s) between MAF and throttle body.

If the parts are currently removed, turn them over and look at the underside for any small cracks or holes.

 

NBCat, thanks for the reply. I have been searching high and low for the possible leak(s) for months now, including (but not limited to) replacing the MAF. Really hoping to resolve this this weekend.

 

Remove the duct work between the MAF and throttle body. Once removed, examine it closely for abrasions, cracks, holes or separations caused by flexing.

Have a look at post 32 of this thread:

https://www.jaguarforums.com/forum/s...-198690/page2/

 

Will do. I will post results.
Thanks!