What would cause a speed surge??

[leenigen]

Well I don't have cruise so thats not the problem. I checked the fuel vent line and thats okay too. How often should that filter on the vent line be replaced though? I can't remember that ever being replaced. I'll keep poking around but I'm not too sure what to look for.
This problem occured just after replacing the glow plugs and controller. I think thats probably just a coincidence but maybe its pertinant info.