88 300SEL -Diagnosis - Expensive

I recently performed tests for fuel distributer upper and lower chamber pressures deceleration shutoff and acceleration enrichment. I followed the MB shop manual test procedures to the letter and found that the CIS controller was malfunctioning and the MB maunal recommended replacement. This is an expensive little devil. Has anyone had any experience with this problem. Is failure of the CIS controller faily common for the 300? Mine has 107,000mi.

[Benzmac]

What is the car doing wrong?

Also, I would look at getting a good used one if it is faulty. I have replaced only 2 or 3 in around 10 years.
But, they do fail...

Benzmac:

Do you know of any good sources of used controllers?

Benzmac;

Can you confirm the fuel distributer lower chamber pressure drop on acceleration? This is part of the acceleration enrichment test from the MB manual. It calls for 5.3 bar(below upper chamber pressure). This looks high to me.