starting problems????

97 4.3 blazer cranks but won't run.i have consistent spark at the coil,but it is errratic or not at all at the plugs.when it does fire it sems to fire at the wrong time,which,bogs the motor from turning momentarily.is this a coil pickup or ignition module trouble.please help, wife wife needs transportation.

Ignition Module, check and replace.

http://www.automotiveforums.com/vbulletin/showthread.php?t=301228