I guess I would have to use a digital multimeter and check the resistance. I looked at the scope and the max voltage input is limited to 250V. Not to mention that no voltage probe is available. Steve has a point about what he stated. Anyways, I found the problem. It was a bad spark plug wire going to cylinder #3. I couldn't believe it because I bought the ignition wires new a little over 2 years ago and what's funny my #3 spark plug fouled almost every two months for the past 2 years to the point that I bought several plugs and put them in my trunk. A new set of Bosch ignition wires should be here tomorrow. Thanks for the input from everyone.
1993 190E 2.6
Advanced Diesel Systems Test and Research Engineer