Regarding the catalyst efficiancy...you have a #3 oxygen sensor that bolts into the catalytic converter. So either that sensor is reading bad or the catalytic converter is bad. Yes this is guess work here, but I would replace the sensor first because that is the cheapest route. If that does not fix the problem I would change the converter.
as far as emissions/engine management goes...the 'Mass Air Flow' sensor, just replace it. It is rare that the computer gives a false reading or a "collateral" reading for this sensor as this is the 2nd sensor read by the computer. The first being either the 'crank shaft' or the 'cam shaft' position sensor.
The TCC being stuck ON is worse than it being stuck off. As
maxwedge advised...get a full scan...you cant perform the scan with the basic OBD II tool...You gotta spend the bucks at a tranny shop.