I love my truck! That said, I have 154,000 miles 2004 F150 Lariat 4x2 5.4l 3V. In my opinion, it runs great with the exception of a very small vibration at a stop light with air conditioner on. Would you automatically replace injectors as a maintenance item? $500+ ? Also in town gas mileage getting less and less at a faster rate than highway driving although both down.

For engine maintenance, I've replaced:
Both VCTs - Motorcraft
Spark Plugs - SP 546 Motorcraft
COPS - MCD
Fuel Filter - Motorcraft
5W-20 Kirkland Synthetic High Mileage with Motorcraft FL 820s Filter
MAF Cleaned
Air cleaner - motorcraft - Original seal exists

Fuel trims, both short terms bounce around zero. Long term Bank 1 zero. Bank 2 at 3.12% at idle, 575 RPM, 6.8 g/s MAF yadda, yadda, yadda.

No codes.

 

see what others have to say too, but here’s what I would start with:

- check for brakes hanging up (use a IR thermometer)

- thorough/proper TB cleaning and then relearn (note this means removal clean replace )

- remove belt: spin / check tensioner and pulleys for bearing noise / drag (consider just replacing them as maint if they have not been replaced, some do this regularly at much less than 150 interval)

- have you maintained / changed the rest of fluids ?

 

Ps: this one may be obvious, but will mention as some people do not do this with regularity:

- make sure tires and properly inflated, balanced, and truck is properly aligned

 

I think they are a rarely fail item.
On an Audi forum I also follow where new parts are more scarce there had been several threads about improvement in idle quality or response under acceleration by sending injectors in to somebody like Mr. injector http://Mrinjector.us for a thorough cleaning. They charge $18 each and it's a few days turnaround so if the truck is your daily that might not work...

 

I apologize for a late reply.

I didn't put in my first post:
Serpentine Belt replaced - Motorcraft. I didn't check the pulleys for play/noise, darnit.
Front brake rotors, pads, and caliper replaced.
Rear brake rotors and pads replaced
Transmission fluid and filter changed once at 150,000 miles - Motorcraft
Rear differential fluid replaced - Motorcraft. Noticed a slight pinion seal leak

I haven't checked brakes for thermal temp. That makes allot of sense. I didn't think of that. The fuel mileage issue started after I replaced the front calipers, twice. It was twice because the reman ones I got, one of them, the seal came out almost immediately and had to be replaced again. Makes me wonder if one of them is slightly dragging. Also, I didn't replace the brake hoses.

My tires are inflated from 30-35 lbs. Seems I need to watch them closer and inflate 35-40 lbs. I do have a TPMS I installed along with the touchscreen ATOTO radio which I LOVE!

Wow. Thank you, Thank you, thank you! I have a direction to go.

 

Herco injectors about 100$ exact factory match.
When you pull throttle body to clean it will give you access to fuel rail.
Very light afternoon work.
Can of throttle body cleaner and tooth brush , rubber gloves.
Could do plugs at that time.