Only cranks...

my guess is if it is cracnking like normal u can stop thinking it is battery, starter, alternator..

it has to be either a flooding issue, fuel or spark.

unless you have cats that are completely plugged.. I have seen piston engines not start due to a plugged cat and once removed it fires right up.

start with the basics..

make sure u have fuel BEFORE and AFTER the filter
make sure u have fuel BEFORE and after the rail (check the return hose)

then make sure you have spark coming out the wires.
make sure u have no large vac leaks
make sure your sensors are ALL plugged in.(especially AFM)

once u do all of this then give us an update.