Just bought a 2006 F150 with the 5.4. It has 134K miles on it. It drove great for about 500 miles over the last couple weeks. Today, when I was in gear at a stoplight, I went to accelerate and the whole truck jerked/lunged forward (kind of like the transmission slipping and then grabbing). I drove for several more miles. Then, when I got to my destination I pulled forward so I could back into a parking spot. When I put it in reverse, it started bucking and jerking. Had to restart the truck once or twice to back into the spot. Now when I put it in gear normally, to drive forward, it feels like it's slipping in and out of gear and it buck and jerks and I'm hearing a grinding noise when the truck is rolling forward. Any help would be greatly appreciated. Truck is in excellent condition, otherwise and seems to have been well taken care of. What could be the problem? Truck idles fine, but as soon as I put it in gear it starts bucking/slipping and barely moves forward when I accelerate.

 

You have bad misfires. It takes a lot to get it to set a code but mode six will tell you by cly the raw computer counts it has toward setting a code . Torque pro app an old android phone plus a blue tooth reader off amazon will tell you a lot .
You probably need a good plug job every 60k miles . Clean all cop connections and maybe new boots on plugs with dielectric grease applied properly . Torque new plugs in at 25 foot pounds not by guess . Do a nice clean job .No off brand or counterfeit plugs . Oem cops are the best just clean them .

 

^^^That's almost 100% exactly how I deal with my 5.4 spark plugs! Since 2008 haven't had any surprise issues with any performance aspects.

 

What code reader did you use? I have BAFX Wifi OBDII diagnostic interface. It uses OBD Fusion app on my iPhone.

 

Update: transmission malfunction, and flashing overdrive light. Just dropped it off at the transmission shop.