Flat spot in 2007 5.4 F150 ,when cruising ang hit

does it have the same acceleration at that speed, if it does not accelerate so well it is called a flat spot and will almost certainly need a good mechanic to sort it out
If acceleration remains as good in this range as through the rest of the rev ange add detail and please resubmit

Could be the TPS. Especially if you have cruise control, use it a lot and tend to stay at the same speed all the time. If you do the TPS contact strip will be worn down at the point where you always set it at (i.e. say 70Mph) the metal contact at that point gets worn away since it sits on the same spot all the time. The rest of it is fine, but that spot is bad, when you hit it the power is temp lost, then returns once it goes past that part. Moral of the story. Don't always cruise at the same speed, your TPS will thank you!

piston rings are gone
also possibility of head gasket blown too

Thats a good one. Going by what you are saying the vehicle has to under a load in order for the vibration to occur. Best guess would be rear end or torque convertor.

Some of these dont use a light you just hit the on button and set cruise remember if brake is hit it shuts down and you must be going over 40mph, if this doesnt work then check your fuses,good luck.

check for a vaccuum leak this is where i would start if it rolled into my shop. possibly a PCV valve sticking or a hole in the hose, this hose should run from the valve cover, or crank case and then to the intake, or carb.

Is it stumbling and hesitating when you hit the gas or go uphill, but OK at idle or light-throttle cruise? If so, change the fuel filter - it's clogging up and can't meet the fuel demands when you ask for more gas (like going up a hill or accelerating).

unplug vacuum advance on the distributor. seal the hose and put a plug on the advance there should be a noticeably deeper groove in the harmonic balancer where the 2 marks should meet up when the light hits them.
in ex. (10 degrees btdc)

DID YOU CHECK THE RECALLS?? MY 93 F150 HAD A RECALL W/ THE CRUISE CONTROLL (WICH I HAVENT DONE..LOL) AND SUPOSIVLY IF IT ISN'T FIXED IT'LL CAUSE A ENGINE FIRE.. ACCORDING TO THE FORD DEALER IF THIS RECALL SERVICE IS PERFORMED IT CAN POSIBLY MAKE THE CRUISE WORK AGAIN.. (MINE DON'T WORK EITHER) I DONO.. MABE IT'S THAT.

How long have you had the F-150? Has it always seemed to be short on power, or is this something new? I suspect it's the engine (need for 2 more cylinders!) I have a 90 F-250, 5.8 V-8, and I think it's lacking power if I tow or put anything in the bed. Fine when it's empty! 5th gear sounds normal, it's really only meant for cruising on the highway, and flat at that. Maybe we should compare gas bills, you might like that 6 cyl a little more. countrycurt0