Idles smooth , but lack of power in accelerating

Check your codes, I believe you will find a bad EGR, MAF or MAP-

Is it a diesel?

As bob_nueske mention check codes. You might also have the injector control module check and make sure your turbo is functioning properly.

still egr ,some delete it on diesels,ford has a recall on crank pos. sw. may help ,the oil system for injectors sludges on some, a solvent for a while may clean up,kreen or 2nd best seafome in oil for while to clean gum may help,had a 350 w 7.3 never again ,no ford again,any cummings or dura, max if any .still not worth it long run dam,shame!

its a 5.4 351 gas

starts out strong in first gear , then it hit second and it just won't go. eventually it does climb the revs and shifts to third. it has a 3spd auto

bump the timing up,no. one, then tune up plugs ect best you can do ,the rear should be lower for the sounds of, it and if it has cats on it at all thats a biggy punch them out

the truck is Stock the way it came in 1996. Always ran good but it has a glich in it. Timing was chk, plugs , air filter, fuel filter, idle sensor, air to fuel sensor , fuel pressure and the Cat is wide open. I ask on here for a logical answer to some one who may known of this issue or maybe fix the issue. To change my gear ratio and hollow my Cats ( illegal) is not the answer I was looking for

carmen, a 351 aint a 5.4 the 5.8 is the 351