The car is a 1990 2.6 190e with unknown mileage. The odometer is frozen at 99k miles. I took my car several weeks ago and it failed because the low speed idle was too high (1400 rpm). They said it kept aborting the test and couldn't complete so they didn't charge me.

I found the air intake hose and air scoop were missing. The Air Intake Temperature sensor was just floating around the engine bay. I found somebody parting their car out and picked up the difficult to find oval shaped intake setup. I also replaced all the vacuum line connections (aside from any hidden in the fender) and found several unplugged, including one to the throttle body.

This effort appears to have fixed the idle problem. Now it fails for high CO%. Here are the numbers.

High speed:

RPM: 2423

HC (PPM): Standard 220, Current 103 (PASS)
CO%: Standard 1.2, Current .56 (PASS)
CO2%: 14.0
O2%: 0.8
NOx(ppm): 0.00
DILUTION(%): Standard >6, Current 14.6 (PASS)

Low Speed:

RPM: 727

HC (PPM): Standard 220, Current 188 (PASS)
CO%: Standard 1.20, Current 1.58 (FAIL)
CO2%: 13.7
O2%: 0.3
NOx (ppm): 0.00
DILUTION(%): Standard >6, Current 15.3

Is there something obvious based on these numbers? I haven't messed with the Air/Mix, but I got this car used and somebody has already defeated the tamper proof ball. So it has been messed with at some point.

Thanks in advance for any help. My inspection sticker expired 5/12 (lol) and eventually I'll get pulled over. The car will be emissions exempt in 2/14 I believe, which grates on my nerves a little.