I thought that was ecoboosts not 5.0?

 

update on this thread. after I started this thread I ran 91 octane for about 10-11 months straight. my two cents is the 6 speed transmission is for better mileage but the trucks that had 4 speeds got decent mileage. I agree with you that sport mode makes the trans shift more like it should all the time. I don't like driving in sport mode all the time because of the aggressive downshifts when braking but the way my truck shifts regularly is ruining my motor. under light acceleration the thing shifts too fast and lugs it. the basic consensus from the posts on here and im reading I appreciate and everyone says its not good to lug it but that's what it does every stinking day. the truck is in 5th gear at around 32-33 mph and again light acceleration is it wants to shift right around 1500-1700 rpm and when the shift happens it drops to 1100 ish rpm. my truck now has 25,500 miles on it and I do love it but this noise I know its a bottom end clanking from lugging it. I stopped at my local dealership (I bought my truck from one like an hour away from me) and talked to a service writer. he said drop it off for a day. they work mon-Friday not Saturday and I use mine for work so I cant. I have time off around thanksgiving and plan on taking it in then. but talking to friends doesn't help. they are like the dealer is going to say "we don't hear anything" and im siking myself up that when that happens im going to hate this truck. I know I have to give them the chance and go through the motion of taking it in but its not bad gas. my truck does it everyday its not good for my motor. I hear the 5.0 motor is amazing im fairly certain my transmission is killing my motor. I don't think I should have to drive in sport mode everyday.

 

Not sure if this would help or not but you could try reseting the PCM, modify how you drive the truck and have your transmission re-learn its "normal" shift map. Maybe someone who's done this can comment.