How expensive is a new coil? How old is the cap, rotor, plugs, and wires? Maybe a ‘tune up’ is in order.
The new coil is about $35 - $40. The current coil, rotor and cap are approximately three years in age. Plugs and wires were installed yesterday.
Have you checked the battery cables for internal corrosion or breaks? May be easier if you can check the voltage at the starter when you try and start without jumping.
My battery cables are the original, 8-gauge factory cables. They appear to be in good condition. However, on a 99 model year, things have had some time to age and run through their life cycles. Perhaps replacing the battery cables with 4-gauge cables, replacing the ignition coil, ICM, distributor rotor and cap will fix my issue - a “tune-up”, indeed, when paired with the spark plugs and wires done on Tuesday.
I seriously believe this problem to be electrical in nature. The engine only has approximately 115,000 miles on it - it’s a rebuilt Jasper engine installed four years ago - engine number three for The Bus.
Any thoughts? Any advice? Thank you, all, for your words of wisdom. They are appreciated. 
- southsidesmoka
An Update:
Unfortunately, it’s not the ignition coil. Replaced to no avail. 
She’s simply not getting a strong electrical signal…why, I am not sure; but, I [I]shall[/I] find out and repair it. 
Open to ideas. Going to replace battery cables. Thank you to all for reading and for any help.
Afternoon Update:
Turns out every distributor cap tower contact and the center contact are all covered with what resembles battery acid build-up. Not sure what it is, but, “there’s your problem”!
Headed to parts store now for new distributor cap and rotor. Any explanation as to how this strange situation happened? I would suspect carbon build-up…but the matter the contacts are covered in is thick and white.
Still having problem after replacing the distributor rotor, distributor cap, ignition coil, spark-plug wires and spark-plugs themselves! She cranks but WILL NOT start without a boost. Help, [I]please[/I]!
And in the end:
I drained the battery below the necessary 12.5 to 12.7 volts needed to turn the engine over while trying to start her. After a few hours on a charger, she’s able to start on her own. The problem was the corrosive build-up on the internal tower connectors of the distributor cap. Learned about the cause of the problem from a GM Service Bulletin. There’s improper ventilation in the distributor cap on some older models which leads to the build-up.
Maybe I can save others some trouble. Maybe not. Anyhow, thank you all for your assistance.
- southsidesmoka
Sounds like someone applied a liberal amount of dielectric grease…