1989 240DL B230F 223,000 +/- Miles

I am in dire need of some emissions help. I have read almost every post I could find on here, including all of the 7xx/9xx FAQ. I am facing Connecticut Emissions testing, and must pass by 6/24/2007 or I can't re-register my brick. Here is my history:

06/17/2005
HC(ppm) Limit: 217 Emissions: 110 = PASS
CO(%) Limit: .70 Emissions: .60 = PASS
NOx(ppm) Limit: 1522 Emissions: 2290 = FAIL
***All tests at RPM 1710, HorsePower: 12.6***

07/13/2005
HC(ppm) Limit: 217 Emissions: 105 = PASS
CO(%) Limit: .70 Emissions: .64 = PASS
NOx(ppm) Limit: 1522 Emissions: 2748 = FAIL
***All tests at RPM 1680, HorsePower: 12.6***
Installed a new rear muffler and tailpipe at this time.

06/06/2007
HC(ppm) Limit: 217 Emissions: 128 = PASS
CO(%) Limit: .70 Emissions: .66 = PASS
NOx(ppm) Limit: 1522 Emissions: 1969 = FAIL
***All tests at RPM 2130, HorsePower: 12.6***

So there are all my stats. Here is a list of repairs within the last two weeks:
New O2 Sensor (installed last night) Bosch Universal, spiced in.
New Valve Cover Gasket
New Oil Filler Cap Gasket
New Breather Box (oil seperator) + Green Gasket/O-Ring
New Intake Manifold Gasket
New Flametrap Kit (Y piece, Short S Hose, New small hose to intake)
Removed coiled metal Flame Trap (per recomendation by Franz)
Cleaned Flametrap hoses
Inspected Accordian hose, no cracks
Removed Airbox, found the flapper was stuck open. Removed flapper, sealed shut so no hot air will be sucked into intake.
Oil Change (+ Gunk Motor Flush, during Breather Box replacement, Crankcase oil hose return was clear, not gunked up whatso ever)

Have been using Lucas Oil brand Fuel Treatment for 1.5 weeks in my gas.
Last night I put in 4 bottles of HEET dry gas, along with 3 oz of Lucas Fuel Treatment, added 5 gallons of fuel. Drove the car total of 50 miles between fillup and test. Air filter was clogged / warped, I removed it for the test. Engine was warmed up for 30 mins + 75MPH drive to emissions testing for 15 mins to get it nice and hot.

Other options I am facing this week:
Replace all hoses that deal with PCV system
Replace Accordian Hose
Clean /replace IAC (+ replace hoses?)
Clean / replace throttle body
Swap out new Air Mass Meter from roomates '89 240DL
Inspect exhaust for cracks, weld cracks if found
Replace CAT


I am looking for any further suggestions, as I don't have alot of money and I am trying to get this done without just replacing every part I can find. The emissions tester menioned that if the car is running hot normally, it will have a problem with NOx (toasted AMM?) If I remember correctly, if an AMM is toast, the engine will run horribly. I know I missed the advance/retarding of the timing by one year (ended in 1988), so that is out of the question.

Any input on getting overall cooler running of the engine to reduce NOX? (clogged CAT = higher temps??)

People have also told me my rings are probably totally gone, so there is no hope except for a rebuild. Any input on that?

Any help on this will be greatly appreciated. Thanks, Brian. bugnacki@gmail.com
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1989 240DL Stock, except for some Virgo's and my stereo.