Yeah, it does seem odd. Kind of an unfortunate coincidence if it turns out to be something totally unrelated.
Not sure about the 5.2, but on the 4.0, there are no starter wires that I can think of that are directly related to anything that would kill the engine. They are dedicated solely to the starter function and don't have any common areas. At least not between the battery and starter that I could see initially. No power take-off circuits like on old GM cars and trucks. No obvious common ground.
Maybe the V8 is different and has such a beast? If so, that'd be where I'd be digging.
Does it die only at lights, or will it act up while driving? If just at idle or near idle speeds, perhaps it's just the ECM needing to realign itself to some sensors that are borderline. Where before it was working ok and knew what to do, now that the battery was disconnected for awhile, it sort of reset itself and is back in a relearning mode?
Any check-engine lights? What about a quick scan with a tool that can pull up codes that don't set the light on? Seems like a bit that would stall the engine would also set the CEL to coming on at least momentarily. But I've seen stranger things on these modern rigs!
Being a '94, you don't have OBD II to help you out. Maybe someone can run you through the procedure to test for hidden codes to head you in the right direction.
Fuel? Yeah, maybe. But does it feel instantaneous like electrical, or is there any bucking and hesitation during the time it's about to stall?
When it dies, does the tachometer instantly go to zero? Or does it slowly go down as the engine stalls?
I would think something like that would set the CEL light to glowing, even if it's not as sophisticated as an OBDII system.
I've never seen an instance on an American vehicle where a defective starter or battery could cause an engine to stall if everything else is working. If your volt gauge tells you the alternator is charging, you have enough juice to run the engine. Even if your battery died, your engine should keep running off the alternator until you turn it off.
But, if the battery or cables were so bad that they couldn't run the engine without the alternator, they'd never be able to crank the engine to get it started in the first place!
So it doesn't make sense from that standpoint.
And if the cables and connections are good enough to start the engine, an alternator could die completely and the engine would still run for a long time on just battery power.
The momentary or intermittent connection you were tracking down could give it fits, but not sure which one it would take going bad to make the engine stall only at a light.
The only thing I can think of that the two systems have in common (and that could cause an engine to stall) would be the computer.
For that I might suspect the main connections (3 or 4 of them?) at the ECM and/or the wire bundles that run out from there to the various parts of the truck.
I guess that not getting a good ground could cause all sorts of issues, so it's good to at least confirm that they're all good, like you already did. I would not hesitate (and didn't in fact) to strip the tape, split-loom, and any wire-ties or other clips away from the wire bundle between the battery, engine, alternator and power center/fuse box there under the hood. Just to make sure all the positive wires are as good as the negatives.
After all, it's simple and easy to replace the covering if you want to.
Look for any junctions that might be corroded under the tape. Clean (again) the ground stud/bolt on the engine block and make sure any secondary cables from there are clean and tight.
Not sure if the layout is the same for the V8, and it probably isn't, but there are always consistent things to check. Just like you found the bad ground cable at the battery, there could be other culprits.
Look for any wire bundles that are near the starter that you could have bumped. Any additional wires on the starter that you don't know where they go, follow them along until you do.
Regarding the battery lug. If you're still having a hard time getting both cables to attach tightly to the lug, get anything that will work. There are the "lead-free" terminal lugs like the factory ones that will accept two wires. I've used the type with a stud and nut for that (rather than the bend-over tab/crimp type). Even the "temporary" kind that have a top strap with two bolts to bite down on a bare cable really work well. They're only meant to be temporary fixes for a failed lug, but they work well!
Sounds like you've already got the cable thing worked out for the grounds, but check the condition of the positive side for sure. That's usually even more damaged with age and corrosion than the negative. Maybe you're just missing another small break like you found on the NEG side?
Kind of an aside, and nothing to help with your issue, but when I use the typical store-bought "starter" cables with the eyelets at both ends, I like to put shrink tubing over the junction between the metal eye and the vinyl jacket. These things are really crimped well at the factory, but I just like to keep as much weather and battery acid out of them as possible. That way they just stay in nicer condition for the decades that you're likely to be using them.
Good luck. I'm just rambling here. Nothing that will guarantee to cure your stalling. Just help with the battery connections. There are a CRAP-ton (scientific term) of threads about stalling V8's. Some with very technical answers. If you haven't already, you might just sit down with a nice refreshing beverage and see what a few hours of searching/reading net you.