when is there a spark at the plugs? when you're holding the starter down?
the symptom of 'fires when cranking, dies when starter released' means the ballast resistor is open [or a bad wire/connection] - try removing the wires from the resistor and clip them together

Bill

Moved over to the Passing Lane

"When we tug a single thing in nature we find it attached to the rest of the world" John Muir
"When we tug a single thing on an old truck, we find it falls off" me
Some TF series details & TF heater pics & Rust-a-holics Unanimous parking lot