Re: two dead clinders at idle, but fine at higher rpm
Vacuum leak, somewhere between those 2 dead cyls. --
A classic symptom.
If it was a head gasket, you'd feel it at higher R's too.
If it was plug wires, a dead DIS coil, cap, switched wires,
crossfiring etc. it would also be there at higher speeds,
Generally a vacuum leak, hose, base/manifold gasket etc, is
a fixed leak size, doesn't get bigger with speed.
But, the total amount of air/fuel mixture does with speed.
So at idle the amount of fresh air getting in is a larger
percentage of the total than at higher speeds - thus why it's
most pronounced at idle.
Higher speeds its virtually overwhelmed by the volume of
Spray a burnable carb cleaner, starting fluid, propane, etc
around the carb base gasket and any vacuum trees close by.
Should be an easy fix.