I have a 1999 Ford f150 v8 4.6 and just replaced the plugs and spark plugs and fuel filter. Prior to doing this it ran just fine but now it like hesitates when you step on it and when you ease into it it wont do it. All the plugs and wires are good already checked that. Any ideas.

 

This may sound out in left field, but Fords work best with Motorcraft plugs, had to learn this the hard way !
When installing the plugs, was the gap checked to be the correct one for your particular vehicle?
Sometimes in the process of replacing plugs some things are moved /disconnected like air filter, Maf sensor etc. Any check engine light?