OK, oh gurus of the 4.6, I am having a serious problem that is thus far kicking my butt: after driving my car for an hour or so, it will start to sputter and hesitate under half-to-full throttle... it first starts to happen at over 4000 RPM, and it'll stop if I let off the throttle some... but then progressively worsens until it starts to do it around 3000 RPM, until the point to where the car will die with any throttle input. No SES light or codes. I already changed plugs, fuel filter, and after many people recommended it to me, I changed the MAF sensor... to no avail. Weather conditions don't seem to be a factor... it does it when it's cool, when it's hot, when it's raining, whatever. If I pull the fuses for the computer and let it sit awhile, it'll run OK for awhile... but always ends up doing the same thing. OMG, please help!!! Anything you can say to help would be very... helpful. Thanks fellas! 
. Check to see if your plugs are bad, it doesn't sound like it but you never know. I had a similar problem and it was my O2 sensors. I would lose power and the car would feel sluggish. One of my extensions was bad. Like the boys have said, check the easy stuff first, plug wires, plugs, that sort of stuff. You just may have a bad plug wire. 
. Sure enough, battery was cracked and leaking.
