2005 5.4 runs rough exhaust leak?
 

Grandson's 5.4 ,2005, missing, running rough using a big amount of fuel. Threw one code, PO 301 then erased it. Found a good size hole in the exhaust before Cad Converter. Would an exhaust leak cause rough running? Removed battery cable to reset computer. Ran find for a while then back to rough. I suppose the computer sees the problem and adjusts to a rich mixture causing the misfires. Any help would be greatly appreciated. Thanks T

Yes a exhaust leak will most definitely cause a vehicle to run rough, since you only have one fault code you should get the exhaust repaired and see if there's any other issues afterwards.

Thanks Scott. Going to go with a temp repair, wrap it, and see if that makes a difference. T

Will an exhaust leak cause a severe loss in power?

If the convertor is plugged it will
Drill a small hole in front of the cat and see if that helps the problem
You can always put a small screw back in it to seal i up