Unexpected stalling !!! Where do i start????

[OUbesto]

Hi guys, been driving my '70 c-10, 402, AT this summer since completing a spring paint job, new interior etc and have had no issues driving 200+ total casual miles until yesterday! Was stopped at a traffic light waiting to turn left. Once traffic cleared and I knew I could get thru the intersection, I started to accelerate to make my turn and heard a "pop" (almost sound of a small backfire) and engine stalled. I put gear shift in neutral (since I was still drifting) but starter did not turn over or do anything! No cranking, no clicking...nada! Thank goodness an oncoming car saw me coming to a stop in the middle of the intersection and stopped or it would have been "T-bone time". I drifted through the turn and finally came to a complete stop. Put shifter in P, engine turned over and started right up...drove another 20-25 miles no unusual sounds, missing etc until about a mile from my house, then it did almost stalled after the "pop" but this time it did not die. then ran fine for final mile home.

Within last month:
- new plugs
- set timing
- new intake manifold
- oil change
- coolant flush
- new fuel filter
- fresh gas about 2 weeks ago



Where do I start to troubleshoot?