Toyota Repair: T-100 emission failure; P0133, air flow meters, air fuel mixture

Question
1995 T-100, stick, 4WD 153k miles Failed emissions. HC 266ppm against limit of 220ppm. Check engine light not on currently or at test time but has been on and off over past several months. P0133 was read by Autozone through OBDII port.

Since test have replaced plugs, PCV valve, changed oil/filter and air filter as part of a normal PM (it was time) . Have a new B1S1 O2 sensor on order to correct the P0133. This sensor has never been changed.

At 57k replaced B1S2 O2 sensor. I will check for exhaust leaks when I install the new O2 sensor. Anything else I should do before I get it re-inspected?  

I also considered a vaccum leak but don't have a clue where to start looking or how to detect if there is one. Any suggestions to help here would be appreciated.

Also, I've read a number of questions on this forum about air flow meters and cleaning them. For my vehicle it doesn't appear to be a two wire type like I've heard (read) you decribe but looks more like the front end of a jet engine. Not what I expected. How do I go about cleaning this style of MAF?

Thanks in advance for the service you provide.  

Answer
Higher than normal HC readings are normally caused by an engine misfire, there are many things that can cause a high HC reading means that there is incomplete combustion and some of the fuel is not burned but expelled into the exhaust system, because of this the O2 sensor sees a lean air fuel mixture and turns the check engine light on, I doubt if the o2 sensor is the problem , it is just monitoring what the conditions are, in this case too much HC(unburned fuel).
There could be a vacuum leak, a tight valve, or a leaking valve or another reason that causes incomplete combustion.
This engine uses a vortex generator type of air flow meter and is not serviceable, it's not the problem anyway, find out why the engine is not running at 100% efficiency.