I brought the 03 into the dealer Monday morning but, before I did I took it to a friend who is extremely knowledgable. He drove the car and said it was a dog, putting out no power... He said it was misfiring and to have the dealer only replace the plugs not thinking the cats were bad... He also mentioned the popping noise that we heard was unburnt gas exploding inside the cats... So then off to the dealer I was... I explained everything to this hard-ass service manager, and he just said "we'll check it out!" I then spoke to the owner of DiBlasi Ford who I got friendly with and he lit a flame under the service guys butts... First they said that the computer showed the plugs where replaced on June 10 by Ford?? Strange, it came off the carrier at my dealer on June 24, so I'm assuming this was done post-manufacturing near the assembly plant after a test drive... They replaced the plugs and said it was still misfiring! After that they disconnected the suspected fouled cats and drove the car! Boy that motherf*cker was LOUD, but sounded kinda nice. When he got back he said it was making full power! Yey! So now they ordered the cats and hopefully I'll have her back in a day or two. The outcome of this long narative post, they said the cause was "defective cats" with also caused the plugs to foul with no sign of bad gas... He said he's seen that in the Lightning truck as well and it's not unlikely that several Cobras got affected.