Audi Repair: Misfires under light load during warmup phase, intense problems, heat tubing

Question
Jan, you've been a great help thus far.  You've helped me look outside the proverbial box and your advice has been priceless!  

I wish I could say that I've found the problem, but...not yet.  

To refresh, I'm working on a 1998 A4 1.8T that has a misfiring problem if I attempt to drive it DURING the warm up phase.  

This is the latest:  I dug into the wiring harness to investigate the wiring and connections as you instructed.  The ground wire (brown/yellow) was in good shape except for the last few inches (probably due to the underhood heat) that actually is fastened to the cylinder ground.  I soldered in the correct gauge and length of new wire and wrapped the whole exposed section in electrical tape and cloth heat tubing.  Prior to the splice, I checked for resistance from ground to each of the coil's ground pin, and they were fine, but I wanted to rule it out as being a problem.  I verified continuity from coil ground to chassis ground and it was also good.

I checked for battery voltage at the fuse 232 and it was correct on both legs of the fuse.  I checked for continuity from the fuse to each coil's power wire (black/blue) and also got B+ voltage.  

I also went ahead and checked the primary ground leg of the coil to the corresponding gate at the ICM to verify their integrity - they were good.  Finally, I made sure that the ICM's ground was also good.

Could I have presumed that a part was good when it wasn't?  Believe me, I hate to replace parts ($$$) as much as you.  But, worse is not making progress on resolving this problem.  I've encountered much more intense problems, but the solutions were NOT this in depth (or mind boggling).

I hate to burden you with my problems, but I really don't have much faith in MY local Audi dealership's ability.  

Grateful for any further advice that you can lend!

Answer
Oh wow,  Didn't think this problem would persist like this, I was sure you were going to find a bad ground.  Looking at the circuit, there is not much that can foul it up.  Although one of my favorite sayings is that car electrics do not follow Ohm's law...  YOURS IS PROOF!  So the only thing causing misfires under low power is going to be perhaps an issue with the vacuum intergrity, or perhaps a coil is breaking down causing high voltage to be going to the wrong place.  I believe you checked the coils etc, but what I have done before is to look at the engine in a very dark area, to see if you can see arcing anywhere.  Easy test, if you must do this in a dark garage please keep doors open.  Must admit I'm glad I'm not in your shoes, these can be a real pain.  Please let me know what you find,  Jan