Followup - Well my second RECYCLED MAF I purchased was the same as the oem numbers and it cured the idle hunting problem and enabled the O2 sensor test mode to provide repeatable results.
I'm seeing a pattern in the many posts on idle and rough running and seem to often be related to aftermarket intakes. The car I was working on, a low miles clean '93/KA24DE also had an "INTAKE" installed shortly before the MAF "**** the bed". Perhaps the filter oil treatments degrade MAF function more than appreciated.
The first replacement MAF I tried was a 40FOO and I believe worked as good or "seat of the pants" dyno test - better than the 53FOO oem model on accel and cruise. I was wondering whether it could be adapted somehow or the idle screwiness fixed.
I also have some interest in the exhaust air inserter (AIV?) system which seems to produce some moisture in the chamber piped to the air cleaner. I don't know if it that is unusual or not. I did remove it's hose from the air cleaner but don't understand if it needs vacuum from the intake or is just sourcing filtered air. I was going to put a small oil breather type air filter on its intake or remove the whole thing if it won't degrade some other system ops.
PS I have FSM on order.
Thanks for the helpful info and the willing ear. - PB
