86 F150 no power highway

I have a 86 F150 straight six, runs great in the city but has no power on the highway. I cleaned the egr valve because it was stalling out, could this be linked to the power loss?

Is it fuel injected? Because if it is I would start at the fuel pressure regulator, Or even the Mass Air Flow sensor. If its not fuel injected i would check the fuel pressure into the carb. or the float level.

How long since fuel filter change?It's down on the left frame out of sight- out of mind.