My sons 05 F150 is randomly dying during low idle. We removed and cleaned the TB and cleaned the MF sensor. For example, if he is coming up to a stop or slowing down, the truck will die, but starts right back up. So far no CEL and truck seems to idle and run fine, just ever so often will die.

Anything to check on the 5.4s

 

Did you disconnect the battery when you cleaned the mass airflow sensor and the throttle body? If not that would reset the PCM. Also did you take the throttle body off to clean it? Is it dying because the idle is so low or bouncing around?

 

When was the last time your son changed the fuel filter... I had a problem something like that...buy mine would hesitate to pick up and then die after idling oddly...

 

The fuel filter is a cheap fix and a great place to start, disconnecting the battery is like hard booting your computer BUT don't forget that there is residual power stored in some of the components and the battery should be disconnected for several minutes.

I know this may "sound" odd but listen and "feel" how the engine stops listen and feel another similar engine, if your's is stopping quickly (I call it hard) then there is a great possibility of a partially seized idler pulley. Take some pictures of the drive belt up front so you can get it back on the right way then remove it.

Spin each of the pulleys they should spin freely and without being lumpy, you won't be able to "spin" the crank.

This little test is fairly quick and will give you an indication of a partially seized idler, water pump, alternator or the free wheeling clutch on the air conditioner.

Before removing the belt take a good look at the alignment.

Drove into a gas station one time (in town) idled up to the pump and shut 'er down filled it up and hit the start and it wouldn't even turn over.

Failing all that have the fuel pump (in the gas tank) checked for rail pressure.
Another possibility is a worn ignition switch and or a poor ECM ground those two are just rotten to find and don't give a code
Hope one of those suggestions helps

Cheers from Studio48
Law of mechanical Repair - After your hands are coated in grease your nose will begin itch and you'll have to pee