My 1989 740GL is a GROSS POLLUTER for NOX

[rob444-960]

Here are the facts.
1989 740GL sat inoperative for seven years. Efforts since have made car run well, cruises at 75 and gets 24 MPG with no smoke or problems except it will not pass NOX.
Cleaned tank and new pump in tank, new gas filter, new pressure regulator and pump relays, plugs, wires, cap and rotor, O2 sensor replaced twice and ECU switched out. EGR and all pipes and hoses cleaned or new as well as vacuum controller. Had the system smoke tested after replacing all intake and exhaust gaskets and hoses and showed no leaks.
The OBD keeps sending 232 and 231 codes [too lean] and sometimes 221 [MAF/AMM] so I have replaced 02 twice and the MAF.
Compression is 195-200 in all cylinders and the front and back of Catalyic converter runs about 365 to 435*. I cleaned cat so I see thru grid and hear no broken elements. I tried adjusting timing, I know the computer controls this but I was getting desperate, and now it is idling poorly as well as setting 232 and 231 codes. My cat shop has told me that the smog numbers don't indicate need for a new cat so I am trying to avoid throwing that cost on this project if it won't help.
Does the "LEAN" results indicated by 232,231 prevent the cat from getting enough fuel to raise combustion temp for effective EGR to lower NOX?
How do I change LEAN problem when I have no vacuum leaks, exhaust leaks and new 02 [OEM BOSCH]doesn't change codes?
Thanks in advance to those who have more tricks in their bag than I as I have depleted mine.
Rob