76 k20 runs then just dies while idling or driving without warning.
 

Chevy 350 with Mallory hei distributor and mallory hyfire cd box. Truck will start right up fine then idle fine then just die after about 30 sec to a minute roughly. doesn't sputter or show any signs that it's going to die either. seems like it stops getting spark all of a sudden. Started doing this after I replaced rotor, cap, wires. Also it will drive fine for about a minute then do the same thing as well. After it dies it usually starts right back up and runs fine but then dies all over again. The odd time It would just keep cranking over and not start till I turned the key back to off position. Any suggestions as to what this is would be great.