When my 450SL (different car, V8 engine) had an intermittent miss at different speeds, particularly idle, I went through the same process you are determining fuel versus ignition, and after seeing what looked like marginal readings to me on an old Sun LS2000 ignition scope I have, I changed the ballasts and ignition wires on general principle, and then (incorrectly, it turned out) moved on to fuel thinking I had good hot spark on all eight. After quite a bit of head scratching over the fuel injection, I went back and used the old school, old fashioned way of isolating a single cylinder miss and found it was electrical after all. With the car idling, I pulled the plug wires one at a time, listening for whether they changed how it was running. This technique is usually used to isolate whether a single cylinder is completely dead, since the engine will run the same with or without the dead cylinder's ignition wire connected, but in my case I was listening for whether disconnecting some cylinders made it a lot worse while others made it just a little worse. Long story short, I found two different cylinders that made a lot of difference, and then with some horsing around moving whole ignition wires from one cylinder's use to another figured out I had (in my brand new set of factory made to length Bosch replacement ignition wires) not one but two flaky wires. I cut off and remade the plug end on them and the problem was solved. Two morals here. First, if I had taken the car to a shop with a big sensitive ignition scope and a technician who knew how to read it, I am sure the two wire ignition miss would have been visible to a trained eye (even though I couldn't see it on my dim, small LS2000 scope). Second, because my ultimately-ignition-wire fault continued even after changing all the ignition wires, it reminds me that just because a part has been changed doesn't mean it isn't (wasn't) the problem. With other kinds of analysis available, not as many mechanics spend the time to read secondary ignition scopes anymore. Be sure before you rule electrical out entirely that someone has "scoped" the ignition system. A good ignition scope is a good tool for hard to find misses in the right hands. This is the tool "Diesel911" was refering to earlier, and I don't think from your posts that it has necessarily been tried. If you want an idea of what that's all about, look here: http://www.babcox.com/editorial/us/us30224.htm.