Just an update on my car situation. I took my car back to the Mercedes mechanics. They said they'd do a smoke test to see if air was coming out anywhere else. They didn't find anything. The problem they found was the relay. They said that it wasn't transmitting info. They replaced it for $408 total, and even though the smoke test was supposed to cost $120, they didn't charge me for it. Now, I'm hoping no one here and tells me I was ripped off. I don't think that I was, and I actually think they were more than fair. I'm glad I found this place. So far, the CEL has not come back on.

So far, this 'check engine' light issue has cost a little over $500. I suppose that's not too bad except that I wish this had not been tied to the inspection (which still has yet to be done because I have to drive 100 miles first). Not to mention the enormous amount of time this has cost me. Fortunately, my son came into the town this weekend so I didn't have to spend 6 hrs at the mechanics yesterday. Anyway, just wanted to give you guys and update. I forgot to ask the Mercedes place which vacuum hose was replaced but I'll call them and ask.