No spark no start condition

Question

2006 Nissan Altima 2.5L, 177,000 miles, well maintained, recent plugs, 4 Coil on Plugs, new crank position sensor, new camshaft positioning sensor. Recent problems rough idle and what sounds like intake backfire on startup. Car died on drive home. I have verified power to coil connectors and gound for coil connectors. I have tested for spark and have none. I swapped the ECM relay for the fog lamp relay, with no effect. The car rolls over normally, but no fire. ODB II had code P2101 (throttle actuator); I erased the code. No trouble code light before this happened.