1994 lss ignition problem

have a 1994 lss with 3.8 with no spark. started out that numbers one and three cylinders would not spark under normal acceleration but would under heavy acceleration until speed was leveled off then they would quit firing again. had shop look at it and they replaced ignition module but it did not fix problem. car is now in my garage and i am trying to check it out. removed front crank pully and checked sensor and back side of pully and found nothing broken. i am going to replace crank sensor if it is not real expensive (144000 miles). need to know what specs are for cam sensor to check it. turned engine over and checked cam button and it is ok. the shop i had it in also tried a new computer and that did not help. also does anyone know where i can find a wiring diagram for ignition system for this model. thanks in advance.