Ford Repair: lack of power under load, ford f 150, vacuum switch

Question
I am working on a 89 Ford F-150 with a 4.9 (inline 6). I was ask to look at it because the guy changed the plugs, wires, fuel filter, distributor cap and rotor, and he still had a miss. What I am seeing with this is it sounds like it loads up under a load. I have found that the EGR valve isn't working. The vacuum switch isn't working. Does the switch run off of 12 volts? Should I be able to apply 12 volts to the switch and it open, with it disconnected of course. And would that even cause this problem. Once it is up to speed driving down the road it seems fine. It just has the miss under load. I have another vacuum switch and another EGR sensor that i am planning on putting on to see of that helps any. Any Ideas??? And yes I double checked everything he did and I also checked the fuel pressure. The EGR issue is the only thing I have been able to find. Thanks for any help

Answer
Go ahead and throw the other egr valve and switch on.Make sure to clean the valve w/ carb. cleaner.Carbon sometimes gets stuck and will cause similar symptoms.Yes the switch should open when 12 volts are applied.Don't forget a new gasket for the valve,yes it matters.