Bad spark plug? Bad plug wire? Bad valve?* Bad piston?*
Do a compression check to check engine internal condition
Vacuum leak is the most common cause.
Fowled sparkplug wire, Or your distributer cap contacts are coroded.It may be a vacuum leak on the intake manifold/throttle body, if not make sure your IAC (idle air control) is functioning OK.
Yes, it can cause low/unstable idle or die off at idle.
A vacuum leak could cause that.
vaccum leak, bad plugs and wires, map sensor, egr vavle, idle air control vavle