So i got ny truck back about two weeks ago from dealership for miss firing and its fine on that pt. But it still backfires around30mph and 50 when i mash the gas. I have an airaid intake system on it and they tried blaming on that because of too much air getting rushed in. But my dad has same intake and engine in his f350 with no problems. Any help?

 

What condition are the plugs? My F150 did that with 50,000 on the plugs. After the plug change there is no more back fires.

 

Im not sure ill call the dealership and see if they checked them. Are they hard to get to on the 5.4 engine?

 

Pretty easy to find out if its the CAI - throw your stock intake back on and see if it goes away. Just b/c t works on a 350 no problem has little relevance - different engine, pulls more air b/c it needs it. Aside from sounding nice, a CAI on an unmodded 150 has yet to be shown to improve power, fuel economy or performance.