I've got an ignition bug. when I leave my jeep parked outside in the cold (+10 to -20 in colorado) it's starts right up, if I park in the heated garage at work it cranks fine but doesn't spark until I start to let off starter, then it usually runs a couple minutes and dies immediately. It takes about 30 seconds of cranking to hit the right 'spot' where the engine gets spark. It also dies randomly and sporadically when driving? Any thoughts?
Runs great otherwise.

'80 CJ7, 258, weber 38, msd offroad 6, msd blaster coil, new ignition switch