Last week, my car had a case of surging idle and stalled out. I thought it might be the throtle body sticking so I proceeded to clean the flame trap and throtle body this weekend. It is truly unbelievable how much gunk washed out!

While I'm at it, I also checked the condition of the air filter, to my surprise, there was a bird nest in the air box. That's probably the true reason why the car stalled. Don't know how the bird could get in there?

I also found a ruptured elbow on the bottom of the vaccum tower. I don't know how long it has been broken. There were no code stored. I replaced it. Test drive the car, it ran great. After 10 minutes or so of driving, got a code 2-4-1. I wonder if reconnecting the vaccum line actually caused the problem. I looked up bay13's link to vacuum leaks. It looked like a different setup. The vacuum tower had the front three tubes blocked out, mine had all of them connected to something or another. Try to find the elbow close to the power steering pump. Could not see anything like it, perhaps I did not look hard enough. I'll try to find it again tonight. Like to get your opinion and experience dealing with EGR system flow fault.