Hmmmm, I bought 2 of these trucks new, kept them for about 20 years each, and if they had a good battery in them, they always started and ran.

One was fairly low mileage when I sold it and it still had all the original ignition components, including the spark plugs.

The other one got new plugs in it once in awhile and a complete tune-up at 100k, basically new plugs, wires, cap, & rotor. At that time I also replaced the original belts, hoses, and front brakes and rotors. It had 180k+ when I sold it and still ran like new, still had the original computer in it too. I did have to replace a relay and a piece on the throttle body on that truck. Also the a/c compressor.

The ONE thing I always did was use genuine Mopar parts, especially electronic components.

I also had a bunch of fwd Shelby cars (bought used) and I found most starting problems were caused by using aftermarket electronic components.

I would start suspecting one of your new parts may be defective. However, I'm a bodyman, not a mechanic so my advice may only be worth what I've charged for it.

Good luck & be sure to post the solution,
Dallas