Very handy. Thanks for the photo. I was trying to envision where the
port for the exhaust air would end up. This picture takes all of the mystery out of it.

The passage must be corked up good and tight. While I had the EGR off I figured I'd take off the 19mm bolt (while running of course) to see if the chamber was clogged, but it was clean... and still no change in the engine speed. The angle does not look tool friendly. I remember when the transducer port clogged I had to use a drill bit to break up the carbon. Hope that's not the case with this.

I don't think the EGR relates to the low RPM problem. I discovered the EGR as a by product while trying to think through the low RPM. I'm still leaning to a defective temp sensor so I'll take the readings and go from there. I've bypassed the aux air valve which didn't change anything, replaced all the gaskets and triple checked the vac hoses. The air bypass to adjust engine speed in the throttle body is clear. The screw to adjust the idle does change the idle speed, but I run out of threads before I can get to 700rpm. I did not change the position of the throttle stop. I figure the throttle is designed to be completely closed at idle. Adjusting the stop would open it, throw off the air and require adjusting the TPS. I can achieve the same thing adjusting the cable but that's not how it's supposed to work.

I tried advancing the timing a couple of degrees. Performance improved but the ping was too much so I backed it down. It could be that the throttle body is just worn out. I'm not known for working the gas pedal (I pick a speed and stick with it), but when you get near 450K in mileage I suppose everything gets loose enough that even small leaks could add up to enough to cause a problem. I'll keep all posted.