Hi
Happy new year.
First time doing this lol. I have a 1999 expedition 5.4 runs
Great from o to 1500 rpm then runs like crap to 2200 rpm
Then runs fine again. Po340 code showed up replaced the cam sensor the same end result. Took it to a ford dealer they wires etc. Found no probkems. Started runninf fine so i picked it from dealership made it almost home and it started running like garbage again. They said it be a diod in alternator so i put a new not remaned alt in didn't work .

 

Don't worry, we'll be gentle with you since it's your first time.
By "runs" do you mean you're in neutral or while driving?

 

Thank you for being gentle lol. It both runs and drives fine
But that rpm range, 1500 to 2200, is the sweat spot for highway driving. If possible keep it simple im a carpenter

 

Since it's doing it while driving it might not be the engine at all. I would focus first on the drivetrain, such as a bad driveshaft u-joint, or even worn ball joints.

 

I have replaced all balljoints and all u joints recently
The engine feels like misfires in that 1500
To 2200 rpm range.

 

That "sweet spot" is where the PCM typically turns the EGR on.
Carefully inspect the vacuum line between the EVR (EGR Vacuum Regulator) and the EGR valve for a vacuum leak.