The K38 is the shiny ice cube relay behind the instrument cluster on the upper left side. You can see it in the picture at the link I posted. You can jumper that relay just to see if that's your problem.

If your neutral safety switch has not been replaced, I think that is a more likely candidate. You really should either buy or build the code reader and check the codes before you start throwing parts at it.

There is a kickdown switch under the gas pedal but I don't think that's causing your intermittent start problem.

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1993 400E, 256,000 miles (totaled)
1994 E420, 200,000+ miles
1995 E420, 201,000 miles