Mazda Repair: 1994 mazda 626 6 cylinder, mass air flow, resistance value

Question
The car starts right up without a problem.After about 5 minutes of driving it starts acting rough like it's missing. It doesn't die but it's like coughing.  my mechanic says to tell you        1. check engine light does not come on
          2. engine runs a little hot
          3. engine runs rich (loads up with fuel. (he says this is the main thing)
          
Randy, my mechanic,  thinks it might be mass air flow cencor
or the coolant temp censor. He ask if I could get the diagnostic procedure for the mass air flow cencor and the coolant temp censor.

thank you so much for your help.  

Answer
Hi Pat thanks for asking
Does the check engine light actually work, it should come on for a few seconds when you put the key to the on position, did he actualy scan the computer for code? If an engine is running rich the most coomon problem for that is a bad oxygen sensor, Get him to set the timing while he is at it as well. To check the mass air flow quickly , have it running, and unplug the sensor, if you notive a change in RPM's then the sensor is ok, and for the cooling temp sensor it can be tested like any other sensor, when the engine warms up the resistance value in the sensor should drop.
Good luck
Chris P