Well before I replace the fuel pump. I took the back seat out and turned the key on you can hear the fuel pump running with no problem at all. doesnt sound like it even dies out. You can start the car runs fine then at around 3500-4000 rpms the car stalls down and/or misfires sounds like it pops from the muffler. I was reading through other sites and same thing is happened to the same year lincoln ls v6. Said he took it to a mechanic and the mechanic knew exactly what it was he changed the jet pump and it was fine puuurrrs like a kitten he says. Wonder about that situation. As in all the scan picked up no codes but only the cats which I knew it was going to do that. (Gutted) Which they have been gutted before this ever happened. So now Im on the guessing level that its either air or fuel related.