Intermittent multiple cylinder misfire

[BrownieSlayer]

Hey everyone first of all I have used this forum for many fixes on my truck and I thank you all for that!
I have a 2000 K3500 7.4 that is having some issues. The one that is getting me now is the truck will run beautifully for 3-4 days and then for no reason will start misfiring. I am at my wits end with this thing and was just wondering if anyone had any ideas? New distributor, wires, plugs, FPR twice, new fuel pump, and I’m sure lots more that I have forgotten. Would an intermittent problem like this be a bad PCM possibly? I just don’t know anymore

 

[HotWheelsBurban]

Hey everyone first of all I have used this forum for many fixes on my truck and I thank you all for that!
I have a 2000 K3500 7.4 that is having some issues. The one that is getting me now is the truck will run beautifully for 3-4 days and then for no reason will start misfiring. I am at my wits end with this thing and was just wondering if anyone had any ideas? New distributor, wires, plugs, FPR twice, new fuel pump, and I’m sure lots more that I have forgotten. Would an intermittent problem like this be a bad PCM possibly? I just don’t know anymore

Possibly, but when you replaced the plug wires, did you get them in the looms properly? If the wires touch, or get close enough to arc, the truck will have misfires. I know the #5 and #7 wires, this is very critical on, since they're next to each other AND adjacent in the firing order.

 

[BrownieSlayer]

Possibly, but when you replaced the plug wires, did you get them in the looms properly? If the wires touch, or get close enough to arc, the truck will have misfires. I know the #5 and #7 wires, this is very critical on, since they're next to each other AND adjacent in the firing order.

Yes I did… the old ones weren’t but I made sure the new ones were in place. One thing I forgot to mention was random other codes popping up then going away within a few minutes sometimes