98 Ranger xlt 4x4.. bucking, wants to stall? I don't know wtf..

[speedfreak87]

Couple of months ago I bought a 98 xlt 4x4, truck ran great! no issues at all. as of the last couple of weeks when I leave work and go to get on the highway, the truck starts bucking when I hit around 65-70 mph up hill.. then it evens out once I get to the top. and doesn't do anymore after that no matter what hill I hit.. only does it when it's cold. It threw a right forward bank 02 code so I replaced all of my 02 sensors and then cleared the codes thinking that was it.. no dice, it's still doing it. does it with a full tank of gas, does it with a 1/4 tank of gas.. There is no other codes coming up so I'm at a loss right now..

 

[Ranger Al]

dirty fuel filter? If you replaced the spark plug onto this truck, it will need to be OEM (MOTORCRAFT). I will misses, as you stated above.

I would start checking the air filter, clean the MAF sensor, and if that doesn't work replace the fuel filter.

 

[speedfreak87]

I'll be changing the filter this week.


However, I did noticed when I back off the gas a little when it's bucking, it stops bucking and smooths out. to me it sounds fuel related.