Hey Folks.... I need some help! I'm fairly knowlegeable when it comes to mechanics, But I Have tried EVERYTHING to get my father in law's truck to run well. Here's what's Happening and What I Have Done:

2006 5.4 Triton.
New Spark Plugs
New Fuel Injectors
New Coil Packs
New MAF Sensor
New Fuel Filter
New ECM (Tuned and Matched)
Fuel Pressure test at fuel rail 28-45 psi.

This Thing still runs like crap! It idles rough, occasionally stalls out at stoplights, and sometimes hesitates when you open the throttle. I replaced all of the above parts, and NOTHING changed. The truck needed the full tuneup that I did, since the plugs hadn't been changed in probably 100k miles, and the fuel filter was FILTHY. My last resort was to inspect the fuel pump, but I have 28-45psi at idle, and 35psi with the ignition on and engine off. Please Point me in the right direction! I am tired of throwing parts at this thing only to be disappointed!
Definitely my LEAST favorite vehicle to work on HAHA

 

It's likely the VCT system is shot; quite common with the 3v engines.

Others I'm sure will chime in and post up some links. Or you can search for VCT 5.4l 3v and take a gander. I assure you, there is a lot of info on here.

My recommendation is to replace the VCTs and guides and get a Melling high flow oil pump.

 

Time to take it to a mechanic who owns a scanner and properly diagnose it.

 

If you haven't yet (especially if you live in the rust bet) check and or replace the Fuel Pump Driver (mounted on the frame rail under the spare) Cheap, easy and can cause the symptoms you are having.

Good luck!

 

^
That isn't a bad idea.

Besides, if it is running rough, it should have pending codes. Scan it and post any codes you find.