2005 Ram 1500 4.7 TIPM removal

I intermittently have weird electrical issues on my new to me 2005 Ram 1500. Feedback on it tends toward it being the TIPM, and my thinking was I would pull it out, open it, and see if there is corrosion. In my quest to do so I have found the nut that holds the main wire(s) running into it is extremely difficult to get moving. I was soaking it in PB Blaster, but had no success getting it off. I hesitate to put all my strength into it as it doesn't look like what it is mounted to would stand up to that. Is there some trick to getting that nut off? At the moment I don't have any weird electrical issues, but I am sure they will start cropping up again. It is also winter here, so this is not something I am in a rush to get to, but if someone has a tip on how to stabilize things to get that nut loose, the rest looks pretty straightforward.

Short of keeping at the those nuts/studs with penetrating oil, can get get any movement out of it at all? Try tightening/loosening maybe?

Other than that. If you're not having problems, given the joy it is these days getting parts and/or service, I'd leave it alone.

Try a 1/4 impact gun, has just enough power but not too much that it will snap the mount, mine is the same, when I went to spray the underneath with krown for corrosion protection. Try forward and backwards a few times and she'll bust loose, usually.