Toyota Repair: T-100 warm weather starts, mass air sensor, mass air flow sensor

Question
-------------------------The system has had an 'evaporator system code' present, but it does not always enter that code when the truck doesn't start immediately. We have been told by a Toyota service tech that the sensor will not throw a code when it is defective.  How do you check a Mass air flow sensor?   
Followup To
Question -
I have a 1997 Toyota T-100, 4wd,x-cab, 6 cyl w/65K miles. When the ambient temp goes above 50F I must engage the starter aprox 10 - 15 seconds to start the truck.  Once the truck runs there is no problem until it sets for a period of time in a warm environment.  I have had diagnostics run and no conclusion can be made of to what the problem may be.  The O2 sensor has been replaced. We also noticed that 3 of the 6 plugs had  mild corrosion on them.  The check engine light does not come one when the problem occurs.  It has been suggested to replace the 'mass air sensor' which cost $568.  We are not sure if it will correct the problem.  

I would appreciate any suggestions that you may have.

Thanks
Answer -
I don't think the mass air flow sensor/air fow meter is the problem because it would turn the check engine light on.
When you had the diagnostic test done were there any trouble codes?
It is difficult for me to understand how you can have this problem without the check engine light coming on and not have a DTC in the computer.  

Answer
When the air flow sensor has a problem it will either log a PO171lean condition or a PO172 too rich fuel mixture condition, so I have to disagree with the technician you are dealing with, an evap failure code will not cause a starting or driveability problem, I still don't know what is going on, something just doesn't sound right, there is one other thing you may want to have have checked,it's the ECU temp sensor, the repair manual has the instructions to check it.