With losing fire, you mean spark?
If so, you replaced the cap and rotor? Your coil could also be the
problem or possibly the wires.
I am not familiar with your truck, nor if it has an ignitor/sensor or
just points.
If it has an ignitor, I'd clean the contacts to it. Also make sure that
this ignitor has a good solid heatsink - they tend to be mounted on a
solid piece of metal but usually need some heatsink compound (radio
shack) under the device to get rid of their heat.

Remco