My 1991 300E has developed a problem with wandering. Oddly, it is not always a problem. Probably 75% of the time it is perfectly normal. The rest of the tie it will really get your attention, like it has a mind of its own. Sometimes I can feel in the steering wheel like something is sticking a little. I had the front end aligned about a years ago. Had the front end checked out at a local MB Indie shop. They said it needed a new idler arm bushing. I replaced that. No change. Problem still comes and goes. The last couple of days it has been really bad. Could this be an issue with power steering pump or steering box issue?

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2012 E350
2006 Callaway SC560