M104 Searches for Idle for a second and then starts missing
 

EDIT:
I think I have it figured out. Bad wires. I haven't changed them yet because I just also figured out I believe the car has a bad head gasket. It white smokes when hot and driven hard.

But last night I decided to work on it for a second and noticed (it was a VERY dark night) while running that I could see arcing through the plug wires. It was faint but there were sparks through the insulation to the valve cover on all 3 wires (or at least two of the three). Also, the number 2 or 3 *the one with the plug wire can't remember* boot on the plug was easy to see that it was arcing to the valve cover whenever there was a mis. So......... seems like I've found the problem.

At this point I'm guessing the common failure of plug wires is the die-electric properties of the insulation. Maybe a ton of electrical tape would fix that! Of course the real fix is to just change the wires.

But on to bigger things. The head gasket!















I have been having a miss (on and off every few seconds but never goes away). I've unplugged injector 3 and it seems to be on that cylinder. I had a hard time getting to injector 4's plug so I couldn't check that cylinder.

When I first start the idle ranges for a bit then smooths. Then it starts missing. It seems more so after a second.

I've replaced:
-Plugs
-Coils
-Boots
-OVP Fuse

The wiring harness looks great in every spot I've cut open (lots of places).

The EGR diaphragm will not even think about holding vacuum. MAybe the EGR is stuck open?