[bad57chevy]

i have a 99 boxster that died while driving it after messing around trying to figure it out i have found that i am getting fuel and it does have spark intermittently when i try to start it it sometimes backfires like it is out of time or something is there anyway that i can check the crank sensor ? it is a 3 wire sensor or any ideas would be a big help could it be a cam sensor? thanks for any info