P0402, is it my EGR valve?

Well I did some further research today. From what I can find, my EGR is electrical, and it’s EGR, MAP and DPFE all in one. Can’t find much when your search for mustang engine, but if you cast a wider net of 4.0 v6 Ford, you start to get some results. Now I’m trying to find back probes for my multimeter to run some electrical tests but I’ve been to like 10 stores (harbor freight, AutoZone, orielys, advanced Auto, multiple instances of them) and cannot find them anywhere.

With what I read, it pretty much means I have to replace the unit no matter what the issue really is, but I’d really like to get a solid confirmation before dropping 100 bucks. This isn’t my first time with this code and last time it wasn’t the EGR. In fact last time i never even find the issue. Just replaced one thing after another. Be