Hi,
I'm wondering if it would be just as quick to just replace the EGR & Tube.
I got a code 5 & 26 when my Engine lite came on. I twisted the black hose with a red tracer off the Up-shift delay switch and that removed the code 26, the code 5 remains. I bought the e320 new in 1994 and it always had a slight irregular idle when it was warmed up, even back then. It was never consistent and the shop could never figure it out. I've been driving it with the lite on since Sept of last year. The car runs fine. That little rough idle comes and goes. I guess if it becomes really bad I should get it fixed. Thanks for you reply