Periodic Non Starting - Cranks But No Combustion

What could be the cause of this? Have replaced the park/neutral safety switch and the Toyota Mechanic found loose wires on the Master Plug-In and repaired the Ignitor Connector. The computer generates no code to identify a problem. Problem still not fixed. I eventually get it to start but do not know why. Fuel pump replaced a couple of years ago.

Model-Year ?
CSA

Toyota started offering the V8 in the 2004 4Runner model. Which engine?