insight, start learning mechanics. saves you weeks of headaches and money lol.
i have the same issue
ive deemed it to be my brake pads for one main reason. it only groans while your brakes are applied. put the truck in neutral or turn slowly without your foot on the brake, say in neutral, and the noise should go away.
sticky pads i cant understand, although mine are original at 6 years old. only other issue is balljoints that are sticky, or tierods that are chattering as they rotate.
BUT, you said the brake service fixed it for a day. THAT RIGHT THERE, tells me its the pads. they sand your pads down and that will take off whatever is causing them to chatter. after driving the issue comes back by using the brakes.
now my suggestion is put on some ceramic pads, not fords metalic ones. i learned to ignore it personally, as im not doing my brakes for a few months. if its bugging you enough though, change your pads out with a different type.
06 Ranger XLT
5.5 Mid travel w/ 2.0 Fox Resi, Deaver F31 w/ 2.0's
8.8, 4.56's w/ Lock Right and 33's
McNeil Fenders and Bedsides