Hello, guys. I need help ony daughter's truck. It's an '03 F-150 Supercrew with the 4.6 Windsor engine. After replacing the tranny, she wanted a Cherry Bomb glasspack (the 12" red one) on it. After installing it, the truck was lacking in power and stuttering. The check engine light gave me a P0304 code, So I cleared the code and switched the coil on plugs with cylinders 1 and 4. After driving it until the check engine light came back on, the code changed to P0301. We found that the previous owner was driving it with 3 different brands of COP's on it so we switched them all to Duralast. It ran good for a couple miles and then started acting like it was gonna die then would take off again. It finally stalled and had to be pulled back home. Can the muffler have too low back pressure and cause this?

 

Also, I have had the 23" version of the same Cherry Bomb ony truck for almost 14 years now and it's still going.