Just reviving to confirm this. Front and rear B springs go on the DRIVER SIDE on US model trucks. I tried the rear with the B on the passenger and A on the driver side and the truck sag'd to the left by 3/4". Swapped the rears around and now it sits perfect. The truck sits perfectly level...
When it doesn't start does your check engine light illuminate with the key on? If not it's probably the old fuse box issue.
I would not just start shotgunning parts.
Wheel spacers have zero impact on reliability, unless installed incorrectly and your wheel falls off. Congrats on the new truck, jealous of the five speed.