1996 K2500 5.7 random misfire

I've got a 1996 K2500 with the 5.7 and it has developed a random misfire. What I cant understand is I am not getting a trouble code, no check engine light. I recently replaced the crank position sensor, and that made no difference, and to my knowledge, that procedure is supposed to trigger the check engine light with a false misfire code, and it didnt.
There are days where it runs fine, and others it chugs so bad, starts hard, and at times you would think there are plug wires in the wrong spot.
Other parts changed: Cam position sensor, fuel filter, plugs and wires, cap and rotor.
I cant figure this out.
ANY help is greatly appreciated.
I am actually thinking of trading it off....

I would verify fuel pressure for starters, 65 psi is required. Is this " chugging" under load, at low speed?

When accelerating, its fine, but at steady throttle driving, it will "chug". I cant feel or hear it just reving the motor in neutral.
What is so baffling is that its random, it doesnt have this problem all the time.

Monday night filled up with fuel, and added a bottle of JB fuel injector cleaner, and it hasnt missed a beat since...
Time will tell, may have just been moisture, but I am also hearing about aftermarket fuel pumps acting up...
Mine has a Carter in it now, I hope thats not the problem.
If it does it again, I will test the fuel pressure, I have a buddy that can do that. Will go from there...

Thanks for the help