Vehicle has 96k miles, 175 psi compression all 8 cylinders, Power and ground pulse to all coils and injectors, no findable vacuum leaks.
This thing idles so poorly, shakes and acts like misfire, but can not be
isolated to any one cylinder, Intake was pulled,and injectors were tested
@40psi, all coils were swaped out one at a time, plugs are new NGK,
Got any Ideas, I sure could use the help. jensenman4@yahoo.com

 

Here are a couple of things to try:

Inspect the plastic accordian air intake tube for air leaks, especially on the bottom where you cannot see. It succumbs to engine heat, springs leaks and pulls more air in past the MAFS which screws up the A/F ratio, especially at idle.

The other thing, clean, or make sure the part load breather is clean. It's on the left bank front of cam cover. There are instructions for cleaning this on some of the stickys. Look on the XK8 forum sticky if you don't find it here.

Clean, make sure you have good connections on the TB harness connector. Use a contact cleaner. on both ends, let dry, inspect that all the terminals are straight/good, reconnect.

Finally, if you have access to another MAFS, try switching it out for a test.

 

Have the timing chain tensioners been replaced? If the answer is "no" or "I don't know", go to the X308 forum and do a search for secondary timing chain tensioners.