im stumped

[Camper Power]

last night i started my truck and for 10 seconds it ran fine but after it started to slow rpm drop till it died. i tried starting it again and even after holding the pedal to the floor it wouldnt start. i let it sit for about half an hour, tried again and it barely started with the pedal floored and i had to keep my foot on the pedal or it would die and it ran horribly. this morning i started it and the same thing. first thing i checked was the coil (i had problems with it a few months back) when i pulled the wires for the 7 and 2 cylinder they had a green powder on them and a dull color, the rest where shiney and clean. i cleaned them up a bit and now the engine runs fine, but im not sure this would cause the problems i had.