97 Chevrolet c3500 454 V8 7.4L

Truck was running fine, check engine light
came on but truck still running fine no
issues in performance. Two days later, truck
ran fine first half of the day, killed it, went
inside for bout 20 minutes came back out to
leave & truck was hard to start, would rough
idle for a few seconds & die. Ran OBD2
Scanner got P1345. Replaced camshaft
sensor & crankshaft sensor, still no start,
replaced fuel pump then realized it was the
fuel pump relay...fixed the relay & truck
started right up. Ran fine til half way thru the
next day then suddenly just died while going
down the fwy. So took cap off the distributor
& saw it had spun the rotor off, so I put a
new rotor on & it started up drove about 10
miles it Backfired (popped) real loud & died
AGAIN. So, I bought another new rotor cap, &
new plugs & wires, hell even went ahead &
bought a new battery...changed those out,
was able to finally get it to start up but was a
rough start & wouldnt idle on its own, had to
keep my foot on the gas petal to keep it
from dying. Had it towed to where it sits now
& hasnt started back up since I towed it
from the fwy. Now, when Im trying to start it
it's steadily popping & won't start at all.