Audi A8 3.7, missing ! Not running on all cylinders

[ian-gts]

Hi, I have an audi a8 3.7

it is missing and not running correctly. their seems to be a problem with number 4.

I have swapped the coil packs and still number 4 aint working. checked wiring and all seems ok and correct voltage etc..

can some one help please.

Thanks, Ian