I have a 2006 f150 5.4 auto trans. 114,000 miles. At about 40 mph as I accelerate the truck shakes as if trans shifting hard or engine miss. If i put transmission in tow haul mode is runs fine. Any ideas???

 

sounds like the tranny to me. id pull the pan and see if you have any broken pieces floating around....or get it flushed.

 

have you had your plugs changed?
it could be a miss, OD just puts it in a higher gear... less likely to miss there

 

Could be a bad injector usually the driver side injector closest to the firewall where the fuel hits first, their notorious for injectors but they are cheap. Like $50. Not saying it is the prob but not something to look over

 

do injectors get noisy when they go bad.. or do they just go bad

 

mine was doing the same thing until i changed the plugs

 

there are numerous posts on here with people having the same problem. most of the posts lead to bad spark plugs or a bad coil

 

Thanks everyone. I think i will change the plugs, i believe they are original. Getting ready to sell and want a clean conscience. Been a good truck. Replaced with a 2010 f150 xlt crew cab with the chrome pkg, side steps with the 6 1/2' bed. The dealership was so hot to sell they delivered it to my house 25 miles away with papers to sign. Always be a ford man...

 

let us know the results!

 

Your truck has two piece plugs that break when you try to remove them so becareful. Read the sticky at the top of the 04-08 section.