This problem is more irratating than anything else.
I have a 99 F250LD 4x4 w/ 5.4L engine. It has 202k miles on it. The truck runs flawlessly other
than the fact it will downshift for a split second and then shift back into high . It seems to only happen after you let off the accelerator and coast,
then as soon as you touch the accelerator it will
downshift just for that split second. It doesn't matter whether you're at high speed or low, just
as long as it's in high gear. I thought it was the tps as it was not back probing the way my repair
manual said it should. No change .The fluid is new , the torque coverter is new and the trans. has a new pump in it. I've
asked this question before only hope someone has
the answer now. Thanks