Ford Repair: intermittent miss in a 2003 mustanf v6 3.8, coil pack, back fire

Question
I have a 2003 mustang with a 3.8 engine. It started to have an intermittent miss, but no code. No the miss is worse and the engine is sluggish up hill. Now the car has a back fire every so often when it misses. I have replaced the plugs, plug wires, coil pack and now the computer and the car still has the miss. I am at a loss as what to do next. this is my daughters car and she has limited resources so I am out of luck as to using the dealer they are too expensive. This car has 109,000 miles and just started having this problem. I really could use any advice you could give, thanks  John

Answer
Start by replacing the fuel filter. Fuel related problems more often than not will not throw a trouble code. If the filter doesn't help, have the fuel pressure tested. Something you need to ask your daughter. Are you an "E" bandit. This is what I call owners that continuously drive the car on less than a quarter of tank. Running out of gas is the worse thing you can do to a fuel pump. The gasoline itself is what lubricates the fuel pump. Test the pressure first, as the pump can be quite expensive to replace.