I got a 99 f250 sd 5.4 liter 5 speed w\ 215k miles . A few miles down the road I noticed I'm getting a steady pulsation feeling from my truck when accelerating at all gears . It doesn't happened at first but after I've gotten a couple miles down the road then it doesn't go away. I can also hear a change in the tone of my engine and exhaust sound from my muffler when it has this steady pulsation . It will still accelerate when it's happening but it struggles to get up to thru the rpms. And at each gear it doesn't start till further down the peddle . Example when im in second I don't feel the sensation till a quarter of way down the peddle as I push it, into 3rd gear its noticed sooner and so on till 5th gear when I barely have to touch the gas peddle and the pulsation is instant. I even get it in reverse . I can push the peddle all the way to the floor at any gear and it continues all the to the floor . Now on idle it runs a tad rough and in nuetrual I can rev the motor and it seams fine. I recall a couple years back having a similar issue and had a check engine light which I don't have inticated at this time . I had the egr valve tested and the DPFR sensor replaced. Fixed that original issue from 2 years ago .

This new issue happened after I got home from fueling up and let the truck sit for a couple hours ....maybe gas related. Doubt it since it doesn't start in till a couple miles down the road after setting for a few hrs. If I jumped in it now from already driving it this morning it would be instant as I leave my house . Any ideas thank you

Update: let the truck sit for 2 days. Took it out this morning for a short drive , nothing wrong for the first couple miles then the issue slowly started to make it's way back . Now it idles rough . Wish I could add the videos I made of it running . Put in super unleaded and some Lucas injector cleaner . Also cleaned the MAC. Nothing changed the symptoms . No check engine light either