Hey guys
I have an 03 f150 xlt with the 4.6 V8. it does fine starting up and driving around between most speed ranges. however when it gets between 50 and 60 mph the engine chugs briefly untill I either put some more throttle on it or get out of the speed range. It happens almost everytime it is put under load like going up a bridge for example. I live in Charleston SC and there are bridges everywhere. The chug is not refelcted on the RPM's but i can feel it in the gas and the cab and hear it. I am guessing it has something to do with an oxygen sensor or a fuel problem. About a year ago the fuel pump was replaced. Was there somethign that didnt fix? Any help would be greatly appreciated. I would love to tear into it but I am in the military and dont have much time. I appreciate any help.
Thanks
Logan

 

I just had this prob with my 02 4.2. It would jerk And such between 50-60 mph and then after that no more well for mine it was the plugs and wires I changed them ad been running fine since. Also ran seafoam threw the vaccum tube and runs even smoother I think. Hope this helps.

 

what do you mean by chug? my truck does some weird stuff every now and then around 1800-2200 rpms regardless of the speed im going. It almost like lags and feels not very smooth in that range... I also have to either put in more gas or drop speed to make it stop...maybe we have the same problem?

 

I changed the plug awhile ago but i never change the wires. Do you think that the wires would make that much of a difference? That sounds like the same exact problem my truck is having right now. Which Vacccum tubes did you run seafoam through?
Thanks