Guys my motor was idleing rough then shut off.next day as i tried to start i heard a pop noise.i used a spark tester and it showed no spark.this is a 1987 350 carb electronic distributor.the dist is the esi type with a built in sensor and the coil is bolted to the block next to the dist.no spark from coil.this is a new dist kit from gm.what and how do i test next.can not afford buying coils.thanks in advance