Hello everyone I need a little guidance on where to start diagnosing.
Driving into work yesterday I noticed my 2008 xj8 started idling weird when sitting at stop lights. The idle will consistently drop down to 400 rpm and bump back up every 3 seconds or so. I notice the odometer will dim a bit everytime it dips down. I bought a can of MAF sensor cleaner and tried cleaning it a couple of times with no difference. The car does not hesitate or stumble when driving any other speed. I'm thinking maybe the MAF sensor needs replaced but on my way home something else weird happened. My display screen started to flicker on and off for a bit. This concerned me thinking maybe the alternator is on its way out which would be odd because I put a new alternator in and have maybe put 7000 miles on it since then. Below are screen shot of the codes I am pulling when I put my code reader on it which all seem to point to the MAF. Should I start with a new MAF or are their some other tests to run first?

 

P0171 is associated with unmetered air
look for leaks between th MAF and TB inlet
Spray ducting exterior with starting fluid or similar
and look for any effect on idling

See also post by Marty on 9/10/24 on this page

 

What brand Maf is on it if possible I just use Denso or Ngk products

 

It has what I assume is the original denso on it right now. Car has 145k miles currently. I did a little spray testing with starter fluid but I will spend a little more time trying that and see what happens.