On one that took me a weak to figure out, it turns out the wires INSIDE of the bulkhead connector for the wiring harness (to the fuse box) had fried. Basically, we'd traced the harness to the key, but couldn't get the power from the key to go back to the ignition portion of the engine... Once we figured out where the broken wire was, we just jumpered the bulkhead connector and it ran fine.
But common sense dictates that is the exception, rather than the rule, and it's more normal to start at the Crank Positon Sensor, and the fender-well relay.
Anyhow, there are only three things needed to make an engine run.
1 Spark at the correct time
2 Fuel and air, at the correct mixture (or close)
3 Compression
Eliminate the obvious, and do a compression test.
Then make sure you've got good fuel, instead of crappy gas/water/dirt etc. Replace the fuel filter(s) just for good measure. Retake the fuel pressure. Make sure the injectors are clean (NOT clogged, a stream of gas doesn't boom, a spray of gas does)
Then start with tracing spark. Is the spark bright? Does it spark when the piston is at top dead center? Or did you jump timing? (how many miles) Keep backtracking the wiring to see if the computer is sending the wrong signals to the ignition / fuel injection?
Good luck
