I have a 2002 F350 with the triton 5.4. For the last week it has been running like crap. I just did my plugs about a month ago. I don't know if it's a miss fire or bad fuel or I don't know what it could be. It's a popping sound coming from my exhaust and when it happens I lose power. It happens off and on. One second it will run fine and normal and the next runs bad. Any idea what it could be. Today I just changed my fuel filter and added STP octane boost and fuel injector cleaner. Haven't seen a difference yet.

 

What was the brand of spark plugs? What was done when the plugs were changed? Was anything used with the plugs, like anti-seize?

Setting all that aside for a moment, have the truck scanned. Find a scanner that can read pending codes. Let us know what codes pop up.

 

motorcraft plugs. no anti-seize. no codes will show cause my check engine is not on and it never came on

 

Your CEL will not come on for a pending code.

 

When changing plugs, you could have torn a COP boot. Easy to do, especially a 12 year old truck.
Try to run it hard for a bit and many times, it will pop a code and CEL.
I agree with redford, check with an OBD ll anyways. More than likely, you pull an engine misfire code. Hopefully not a random misfire but cylinder specific.
You might see a bad boot as suspected.