When i come up to a stop the truck will drop a few hundred rpm's than it should and then it will catch itself and bring it back to normal idle. i took muffler off and it has about a foot of pipe behind the cab and its straight through. i also just replaced the fuel filter yesterday and after i did this the check engine light came on. i figured it was something to do with the fuel system so i took the -neg- batterie terminal off for about 10 min then re-conected it. it went away. today i noticed that it had a slight stumble when i come to a stop. if the light comes back on i will check for codes but could it be just from unhooking the batterie and the computer hasent learned everything back yet? Thanks

sorry forgot to add that the truck is a 2004 reg cab stx 4x4 with about 94000 and a 4.6