RV need help Chevrolet forum was a waste of time....
And if it's not a coil pack chk that plug wire.
Also some of the HEI systems will blow a hole through the rotor and jump to the rotor shaft for a ground. (Even intermitantly on one cylinder)
More info would be good.
What motor
What ign system
individual injectors, or throttle body?
That kind of info.