[CSGAS]

That's an OK filter for now, while we're ironing out the "bugs" because we can see through it, but remember it doesn't meet GM specs for the GF61 filter nor NSRA safety specs, both of which require a metal housing. That particular one is a Chinese "equivalent", which at first makes it suspect, but I use similar products from NAPA (made by Wix though) while checking my fuel systems out (then swap later too)

How's it look? anything floating in it? Looks like it's coming apart or clogged?

If the new cap is being eaten alive, my first place to look would be the assembly for the button and bushing under the coil. The button should protrude through the hole in the cap by enough to contact the rotor, about 3/8 of an inch. I say check this first because it is a precaution usually overlooked and I've had one that was wrong (the bushing was sandwiched between the button and cap instead of between the coil and button like it should) but this is not the most likely cause.

More likely, something is causing more resistance to passing the spark through the correct path than the incorrect paths offer.

Check your plug gap, it should be .045" or very close (do not exceed .055" on mild engines) and each plug wire needs to be seated with a firm "click" on the ends of the terminals and plugs. Check each plug wire for burns or indications of heat. If you know the specs for your plug wires, check the resistance with a multimeter or voltmeter. For 20000 ohm resistor wires, you should max out about 12 ohms on your longest wire.

Remember, only go to those lengths if the cap is going bad again--but CHECK the cap.

Most likely of all, the new cap will be good. I'd bet the plugs are fouled, either from not warming up still or from the earlier trouble. Check the filter and cap and then go on to check the plugs either when you pull them as above, or on their own if you did not have to pull them above. Notice I listed the order of events based on what takes the least time, money and effort; not the most likely. Even if you get to pulling plugs and find them dark and sooty or anything else that still looks "rich or incomplete" you can buy a set of Autolites cheap still nearly anywhere.

If the last situation is the case, looking at leaning out the carb up to a half turn at idle, resetting timing, or just making sure you drive the truck long enough to come to full temperature (burn the plugs clean) before any more radical measures. We'll see how this turns out and hope to hear good news from you soon!