Hello and Thank you in advance for any help or suggestions!

I have a 1983 Chevrolet conversion van. I am trying to pass the emissions portion to finish registration here in Ca (San Diego). My nox were too high.

Upon research and digging, noticed no effect on the quality of idle when the egr was manually opened. I have removed and cleaned the egr valve and tests fine.
The weird thing is the egr passage into the intake seems to be plugged. I have soaked it, attacked it with a host of flexible cleaning tools to attempt to get through any carbon, and even used compressed air. (after which I would note a bit of atomized air being pushed from the valve cover breather line... so wondered if that meant I was getting through??
The craziest thing is there is absolutely no vacuum at the manifold opening for the egr. Is it really that plugged? It doesn't look too bad. I have reassembled the egr and applied vacuum to the egr valve. It opens and remains so, but the engine doesn't even notice, the idle is not affected.
So what is up? Do I just need to bite the bullet and remove the intake? Is it likely it is that plugged or is there another possible explanation and/or remedy?

My second question is where is the 02 sensor supposed to be hiding. I figured I would just put one in as they are very reasonable, but I can't find it on my van? I've looked at the exhaust front to back and top to bottom... no luck. I am pretty sure all van had them in 1983!!?? My van is still stock with the factory 305 and all vacuum lines etc intact that I can tell anyway.

 

i would bet the intake crossover passage under the egr valve in thr intake manifold is caked solid with carbon and possibly the cylinder head's from unburned oil .i used to run into this all the time in the machine shop .usually with car's and truck's with a lot of miles and oil consumption .you might have to pull the intake and head's and have them hot tanked and rebuilt .

 

Well thank you for that, may end up going that route as it's looking.
I'm not sure as to miles on the motor, I know the tranny is very fresh. The intake passage is clear and clean as far as I can tell (especially since I've been working at it). I can literally get about 8-9 inches of line, wire, vacuum line, before I run into an abrubt turn or dead end of some sort.

Thank you for that info Old Guy. May end up going that route sooner than later. Will post my findings or remedy either way.