All started about a month ago. Truck stalls. Battery light blinks irradically, tach goes haywire, back fires, white smoke etc.

Last night I actually saw flames come out of exhaust followed by white smoke and truck stalled. Kinda sucks at 50 mph with no brakes steering etc...
Not sure where to begin with this major problem.
I have changed fuel filter 3 times in last 5000 miles. I tried disconnecting juice and problem was the same.

I would start right at the bale connections where you plug in the juice and confirm all pins are forward not making intermediate contact.