Could someone direct me to the location of the MAF sensor on
the 99 F150 4.2L? Is it the sensor that is a couple of inches from the air cleaner that plugs into the hose?

 

It sounds like you found it. Here is what mine looks like on my 99 F150 5.4L engine...

 

yea its in the big bell looking tube you can pry it apart with a screw driver then unbolt the 4 bolts holding it on.

the other sensor the one i think you are talking about that plugs into the hose right after the air cleaner is the Intake Air Temp sensor