I was in there a couple of weeks ago to order parts for my transmission cooler install on my GX. They were 60 dollars more than Bell Lexus and Bell was offering free shipping. I think my days as being an American Toyota customer are waning. I'll just order online now unless its something I need...
Nice GX! I'll bring my GX to the February breakfast if I can. Mine has a mild Dobinsons lift and Metaltech sliders. Next up for me is a roof rack. Probably go with a Gamiviti like krazykat69 has. Jeff's GX build is a great platform.
Also, it could be something in the ECU that's temperature sensitive. Could be a ground problem in the TPS circuit. Not sure how accessible the ECU is on the 100, but you could try removing it and keeping it inside where it's warm, then on a cold morning install it and see what happens.
I was in the dealership parts business for 33 years. Mostly with Ford and a few years with Chrysler. I can say from experience that the industry has been in decline for quite awhile. Most dealers are now corporate owned and thus do not offer a living wage. Most dealers have one guy that knows...
Any neighbors experiencing anything? That's strange that symptoms only happen on Wednesdays and Sundays. That would make it seem like something external and not internal in the house.