[Gmecm] Failing Calif SMOG

[Roger and Carol]

?94 Chevy 5.7L V8 with Edelbrock MPFI. ECM 16171199, with EPROM tuned by Edelbrock, based on broad cast code BDUY.
The engine failed recent SMOG test with a CO reading on the ?high idle? test of 2.06% at 2635 RPM; max CO allowed is 1.00%. 
CO at ?idle? measured .03%, at 649 RPM, which was well within the limit.
My BLM?s at 2500 RPM read 130 on my scanner, which I believe means the PROM?s fuel map is biased ?lean?, and the ECM is compensating as it should. I?m confused as to how the BLM?s can indicate that the ECM has control over the fuel ratio but the exhaust gas (SMOG test machine) indicates a ?rich? condition, which results in high CO? Note that CO at idle was .03%, which is well within the limit, thus at idle fuel mixture is correct.
This engine has only one O2 sensor, which is located in the driver?s side exhaust manifold (manual trans applications only). Does it make since that the cause for the rich condition is probably associated with the passenger-side only (not any sensor that affects all cylinders, like the MAP), and therefore not ?sensed? by the O2 sensor? Since I have Edelbrock?s MPFI, I think it could be an injector problem on the right bank only. Edelbrock?s system is batch fire, by the way. Inputs from ?fresh? minds would be appreciated.
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