Mercedes Benz repair: 96 E320 91k, Hartford Ct; Odd check engine /SRS light problem, discernable pattern, dollar signs

Question
Had problem for 3+ years. Check engine light would come on intermittently, stay on for several days and then go off. No discernable pattern. Code was read several times and always was p1444. However (this MAY be important) code could not be read unless car remained running while the light was on. The result of connecting up the code reader erased the codes and nothing was ever stored in memory. Had purge switch replaced, EGR valve replaced and tubes going to EGR valve were cleaned, although mechanic said they were not dirty. No help. I determined that I could shut off the check engine light by turning the ignition switch on and off without starting approx. 10-12 times. It then might stay off for an hour or several weeks. One time in doing that "fix", the SRS light came on instead, very dim. I also heard a static noise on the satellite radio plugged into the power port. Also, the windshield wipers slowed down clearly indicating some sort of power issue. (car still ran fine as always). I "fixed " this by unplugging the radio and the SRS light came on bright and then went out, just like when starting the car. I left the Satellite radio unplugged for several weeks but SRS light issue still repeated even without the radio plugged in. Again I could turn off by plugging in the radio-again came on bright and then went out. Whenever the SRS light issue is happening, the Check Engine light NEVER comes on. Likewise when the check engine light problem is occurring, the SRS light issue never happens.  Seems like some sort of electrical problem rather than SRS or P1444. Mechanic gave up and the only dealer reasonable close has tried to charge me several times for other items that did not need repair. I'm sure this issue would bring Big dollar signs to their eyes. Help!


Answer
My first concern is this issue:

MB Wiring Harness Failure
http://www.mercedesshop.com/shopforum/showthread.php?p=927185


Purge valve 96 E320 code P1444
http://www.mercedesshop.com/shopforum/showthread.php?p=658096


ShopForum > General Discussion > Good MB Shops > Connecticut  
Connecticut  
http://www.mercedesshop.com/shopforum/showthread.php?p=1230426