96 gmc yukon crank but no start

ok im beating my head against a wall here 96 gmc yukon vortec 350 cranks but wont start has 55 psi of fuel pressure has spark truck is acting like the timing is off it will cough and sputter but not actually fire when my mom first got it it had a code for a cam position sensor but it ran just fine then it just stopped obviously im suspecting the cam position sensor but if thats the case why does it have spark? i am also considering the option that it jumped a tooth on the timing chain but im hoping that isnt it since it was just crusing at 45 when it stopped running cant check codes anymore because it sat after i got it home and killed the battery clearing any stored codes