Mike, I hate these problems they are so frustrating to figure out.
By the way my coil did caused stumbles on acceleration, not at rpm. It was great at speed not to say it is not the coil but I think it is the signal to the lambda that is fishy. If you disconnect the eha does she run better that takes the electronic control system out of the picture. Which other than starting should run the car on the default settings. It also masked my coil in that my stumble on acceleration was almost entirely gone but, not completely, hence chasing the fuel system instead of the darn coil. I have however found steve's advice invaluable, EHA readings are the first place to start then go from there. Keep us in the loop.
m

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Martin Ingram
Colorado Springs
2005 320 CDI
2006.5 VW Jetta TDI
1991 560SEL (179000 Sold)
1972 280SEL 4.5 ('The Lead Sled' 320000 miles when sold.)
1972 220D (225000 when sold)