surging at speed

[jmax33]

truck started surging at around 50mph, dont notice it when on up hill grade or on the throttle, any ideas?

 

[custom8726]

Any codes? When is the last time you changed your fuel filter?

 

[jmax33]

no codes, fuel filter changed about 5k miles ago, i did just fill up with fuel think it could be some bad diesel fuel

 

[jmax33]

truck runs fine today, no idea what was wrong, must have fixed itself!