Is the MAF sensor the 1st sensor after the air box? What is the 2nd sensor? Also what is the best way to go about cleaning the MAF and the other sensor? This is on a 2000 F150 with the 5.4

 

The maf is in a large plasitic tube that is within the airbox on stock vehicles (or used to be anyway, could be different nowadays) The second inline sensor is your IAT sensor (Intake air Temperature) You'll never need to really clean the IAT, but the maf could occasionally use a cleaning. (I just use the ol can of BPC and shoot it off)

 

Go to your local parts store and get a can (aerosol) of electical component cleaner...

just spray the Maf and let it dry (few minutes) the liquid evaporates pretty quickly