Ok, seems you are on a logical trail. IF you have fuel and no spark, go for it. But, you need to replace the rear sensor as you mentioned in the first place. I think I misunderstood and began to lead you to the wrong sensor. You want the one in the rear, yes, I think you have to drip the drip pan from the bottom of the car to get at it easily and it has a wire harness that plugs directly into the EZL on the driver's fender apron. It is part number #11 on the diagram I posted.

__________________
Christopher Henkel
1990 190E 2.6 - Arctic white SOLD
1986 190E-16v - Blauswartze
1993 300CE - SOLD
2003 W208 CLK 320 Cabriolet - Magma Red