I just stumbled across a new issue on my 04 tl 5at with 198k miles, the issue being at higher rpm the car misfires, all cylinders misfire except cylinder 6, all 6 of my ignition coils, spark plugs are brand new and are oem parts, my valves are adjusted and I cleaned my egr not long ago, on shop key I came across a tsb that described my exact issue and it says that I need to update the ecm/pcm with the hds problem being is that I do not have one of those. Just wondering if there is anther known way to update the ECM/PCM without the hds or will I have to take my first trip to the stealership, any input would be greatly appreciated, thank you.

 

If the car has been fine all these years don't believe the update will help.
Usually the 300 series is a problem that affects all cylinders, e.g. vacuum leak, egr, fuel pressure just to name a few.

 

Did you ever end up doing it having similar problems right now