OK so O2s aren't reversed, have you checked fuel pressure?
Something to try. Leave the vacuum for the EGR valve disconnected(plug the line), clear all codes and drive it to see what comes back. You will still get EGR codes but do the lean code remain or go away? If they remain then EGR isn't causing the lean codes.

 

Okay, so when I plug the EGR hose I get an insufficient flow code but STILL get the lean codes. I’m not sure why it took me so long to get there but today for the first time I pulled the IAC valve. It seems to be stuck open. I’m going to replace it and see what that goes. I’m pretty sure that could be what’s causing the lean codes but I’m not sure that it will help the excessive EGR flow.

thanks for all your help!!!!

 

Okay, I think we’ve taken one step in the right direction. The IAC solenoid was definitely toast. So the IAC has been stuck open all this time. I replaced it and it’s gotten rid of the EGR excessive code. It’s also reduced my long term trims from around 30 to about 18. I didn’t get any lean codes while it idled for a while but they turned up while I was driving again.

It’s worth noting that while I was being a human smoke machine the only two places I saw smoke coming out of was the IAC and what I THINK is the PCV valve at the rear of the intake (photo). It seems like the valve is pretty loosely inserted in the hole.

 

The PVC valve sits in a rubber grommet, is the grommet there? If it is but fits really lose a new one is a good idea.

Strange that you didn't have a run away idle with the IAC valve stuck open.

 

Yeah, the grommet is there but it does feel a little loose. I’ve ordered a new one and a new valve too.

Don’t know why I didn’t have a runaway idle. Valve stuck partly open? Looked like a small gap but not full open. Not sure... but it’s definitely improved the trims.

 

So, Conanski, I'm not sure whether to be ecstatic or humiliated!! I got the new PCV valve and grommet and installed. Went for a little drive and the codes came straight back. No help at all. Son of a... we still have unmetered air coming in. Next step has to be to pull the upper intake... Then I remembered the little screen that came off the original MAF housing. I ferreted it out and realized that there wasn't a good way to mount it. So I found a $7 piece of mosquito netting and stretched it over the last join before the MAF. Would you frikkin believe it, codes gone. Trims pretty much zero.

So there WAS unmetered air going in because somehow I had a funky flow of air through the MAF that the sensor didn't account for. So, in the end it seems like that little screen is a key component! Why am I surprised? If the engineers put it there in the first place...?? IN the end I guess it forced me to find and fix a bunch of other little issues too. I'm happy! Thanks for sticking with me!

 

Hey good work. Those MAF meters are notoriously sensitive, just clocking them off center a little bit will change the readings.