2004 5.4l engine dies intermittently
 

I just purchased a 2004 F150 XLT with the 5.4 Triton engine a few months ago and it has started to die at idle. No problem restarting (usually). Its not throwing any codes and due to my online research I replaced the fuel pump module with spacers....no help. My mechanic has performed extensive troubleshooting but there is no pattern to the symptom.
162,000 miles.

Any help appreciated

Does it happen only after the vehicle is warmed up, or at any time?
These vehicles are unfortunately prone to issues with the vct system when the engine is warm and the oil thins out. One of the possible symptoms is possible stalling if one of the phasers gets stuck in a retarded valve timing position when it needs to return to the base Advanced position.

What kind of oil are you running? A lot of people have improved success with running 5w30 or 0w40 instead of the original 5w20

what did mechanic test/do?

Will it ever die at highway speed (or only at stop/idle)?

Does it ever die if it just sits there idling, or is it only if it’s been driving/warm and then you slow/stop to idle ?

When it does die, is time/rest the only thing required to get it to restart?

Fuel/Air/Spark

You need a scanner like torque pro to look at fuel trims . I would see if it leans towards a vacuum leak . At idle the engine is very sensitive to vac leaks as ratio gets way off if unmetered air getting in . O2 will see to much oxygen and will try to add fuel if vac leak . It should be in closed loop with very low short term /long term readings . Torque pro will list by cyl any raw computer counts building towards setting a code for misfires .
You can also see o2 switching as normal or a dead o2. Heater must be working on o2 -common to blow a fuse on that heater if wires get burnt from exhaust manifold .
Plugs/boots are only good for 60k miles. clean cop terminals . Injectors are bad around this year - youtube test and clean diy .

I'm a little let down that you didn't do it:
S- Spark
A - Air
F - Fuel
E - Exhaust

That's how we learned it in class.

Damn... High School was a long time ago and I was just too busy chasing those girls.

My 01 had clogged up cat converters. Had them cut out and all was good. To much back pressure when idling I think. Mine died every time I stopped.

what did mechanic test/do? OTHER THAN SCAN FOR CODES ONLY CLEANED THE THROTTLE BODY

Will it ever die at highway speed (or only at stop/idle)? STOP/IDLE ONLY

Does it ever die if it just sits there idling, or is it only if it’s been driving/warm and then you slow/stop to idle ?

When it does die, is time/rest the only thing required to get it to restart? WORST CASE AS IT IS ATTEMPTING TO DIE I CAN WORK THE THROTTLE AND EVENTUALLY IT RESUMES NORMAL RPM

I HAVE CHANGED THE FUEL PUMP MODULE AND INSTALLED A NEW THROTTLE BODY WITH A NEW THROTTLE POSITION SENSOR

Any update? My truck died twice at idle in a drive-thru this evening. Started right back up but disconcerting to say the least.