The egr valve position sensor has 3 wires a power wire a ground wire and then a brown and green one that appears to go to the EEC. this may be a dumb question but im not exactly the most experienced as far as the electrical systems in these trucks.....or any trucks at this point. however should that green and brown wire that i believe goes to the eec have power? i ask because i seen in another thread that you should test those wires and i have a code for the EVP/EPT circuit being below voltage and it cant be the power wire going to the sensor because that is at the proper range for voltage to the sensor. could a vacuum leak or anything else cause that sort of code? i have a couple other problems also mainly while im driving if the truck has overdrive turned on (the light on the dashboard not illuminated) the truck will drop in rpm and have a serious lack of power but it only seems to do it periodically and i dont think it happens when the overdrive is turned off but im not entirely sure the codes i have are 327 EVP/EPT voltage 332 insufficient egr flow 632 overdrive transmission cancel switch no action during self engine run test and thats it so i figured id check the egr because i cant find a whole lot of info on the overdrive issue other than a fuse or wiring to the switch but the switch seems to work fine the light is only on if you hit the button and i checked the fuse and its fine and i tried using a device that plugs into the egr sensor harness that is supposed to delete the egr system but that didnt work either and i checked all of the vacuum lines visually and cant find any leaks or cracks and i have checked the 3 wires going to the sensor and 1 has power and 1 has ground but the other one i get nothing which happens to go to the eec so im kind of lost and both confused and running out of things that i can check the IAC was changed recently but i didnt check it and im not getting a code for it and the TPS was changed but i didnt check that either
edit: i forgot but i also recently re did the transmission wiring harness not sure if thats related also the engine is a 7.5l 460 in a 91 f250 4x4 xlt lariat

 

Here's a pretty good video on testing EGR components.
While you're checking for engine codes, during the engine running part of the code check, you need to turn the overdrive on and off. That could be the reason for the overdrive related code.
How are you getting your engine codes? If you're using the "count the check engine light flashes" method, cycle the overdrive button after the 4 flashes that identify the engine, near the beginning of the key on engine running test.
RPMs dropping and loss of power could be the truck shifting into overdrive, if it's happening at highway speeds. These trucks didn't make big numbers in horsepower and torque like newer trucks do.

 

that makes sense because i also got the codes for not hitting the gas during the test and i figured out that was the issue and i guess im supposed to be doing things during the running tests and it doesnt happen at highway speeds or at least hasnt in the past and it never used to do it at all but it seems to do it while driving up hills but im not really sure i know you shouldnt have overdrive active while going up steep hills thats why i usually just turn it off becasue the place i live has tons of hills but i just wouldnt expect the overdrive to function like that it will kick the rpm down to arround 900-1000 while accelerating however i have a roughish idle and a slight shake in the motor during idle i would assume thats the egr causing that issue? im new to this can i post a video of the idle and would you be able to tell me if its normal im pretty good at working on things and on vehicles but its a hobby and ive only been working on the old trucks for a couple years so i dont know if its a normal idle or not
edit:i just notcied you put a video on your post ill take a look at that thank you very much