Hi, I have a 2007 F-150 5.4L V3 Lariat with 90,000 miles on it. For about 5-6 months now I have noticed a strong sputtering when I am driving at low RPM's around the 44-50 mph range. When I lightly give it gas the sputtering begins and doesn't cease until I accelerate out of the current gear into a higher RPM/speed. This has become more pronounced over the last few weeks so my mechanic replaced the fuel flter and checked to make sure the pump was working as well. We also added some 5w-30 oil to make it full, even though 5-20 is preferred. Truck ran smooth initially but then it got worse with the sputterring. A couple of days later I filled up my gas tank and as I pulled out of the station my truck shuttered alot and died. the CEL came on, LOP came on, and even the low tire pressure light came on. The truck will not start now, but it cranks smooth and strong until the battery loses power. I had the truck towed and then we reset the gas shut of toggle, sprayed starting fluid in the air intake, and checked all fuses, as well as the fuel pump engagement. Still no ignition. Next we replaced all spark plugs(4.5 hours later). Still no ignition. Only CEL light and low tire pressure light. Any help on this piece crap that I bought used less than 18 months ago?

 

If you have a few Check engine light I would connect a code reader and see what codes your getting...
As far as the truck being a piece a crap I couldnt disagree more. I have a 2007 5.4 fx2 and its the best truck I have ever had. Has 70,000 and have done nothing but normal maintance. Maybe the owner that had the truck before you didnt take care of it or messed something up and sold the truck.

 

Sounds like you could have one or multiple cylinders misfiring. Mine would do the same in O/D around that speed. I found one COP electrical connection not fully seated. I had to dig out the orange oring seal on the truck side wiring harness before I could get it to fully seat. Your just wasting time until you have the codes read...

I have not had to wrench on this one yet but sounds like your not getting fire? hmm bad coils or bad signal to coils. There is a spot where the COP harness run's by an A/C line/component and rubs through. Have you taken off a COP and used one of your old plugs to see if there's fire? Did you take out a plug after cranking to see if its soaked with fuel? Did a continuity test from COP side harness to ECU?

Keep in mind my F150 has 360k on the original 5.4 :P