Just an update on the repair.
I got the car back from the mechanic, and he performed the cleaning procedure on the hot inlet pipe to the intake manifold. It actually was pcv vapors leaving behind carbon that plugged up the pipe.
When I got the car back home in the garage, I unplugged the green vacuum line. Sprayed some brake cleaner in there and blew the heck out of it with my air hose. It's a very small diameter hose and hard to clean it out. When I blasted it with the air hose, brake cleaner sprayed everywhere and the hose flew out of my hand across the garage floor.
I then pulled the plastic off the gauge cluster and had a terrible time trying to put the bulb for the check engine light back on. Must have spend 2 hours. I finally used some tongs from the kitchen, like the kind you use when your frying chicken, and put on disposable rubber gloves over the end of the tongs - like the kind your proctologist uses when he says "bend over and grab the table!".
My only regret is that I kind of put some minor scratches to the black trim around the ac vent to the right of the gauge cluster.
I touched it up with a black sharpee pen and it basically covered up the scratches.
It's been a whole week and the light hasn't come back on yet!
I find myself continually staring at the check engine light, though, waiting for it to come on while I'm driving, and I'm afraid I'm going to rear-end someone driving back and forth to work!
2001 E430, Bourdeaux Red, Oyster interior.
1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".