And positively eliminate that as a possibility of a surging idle ? My 95 E320 has been giving me fits for about a month now. I have decided the wiring harness is not the cause as I have cut it apart in numerous places and it is like new. Plugs and wires are 1 year old. Purge valve seems to be working, the O2 sensor and the water temp sensors are new. There are no leaks in the intake as it was just off for the EGR tube replacement and all fittings are tight. I have good ground at the O2 sensor and have cleaned the MAF. The obvious vaccum lines are good and connected but I would like to be sure that vaccum is not the problem. I read in one thread that a mechanic found a vaccum leak in about 15 minutes that wasn't obvious. How do they do that ? Oh yeah,,, still getting code 13 on pin 8.

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