No, don't worry about pins 13 and 14. It's tough when it's intermittant and not throwing a fault code. Do you have a stethoscope to listen to the injectors firing? I'd guess it's spark just because of timing. I'm scared to put anything but Bosch F8DC4s in the car but that may be an irrational fear. These things - http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=36258 - are nice for checking spark if you're close to a Harbor Freight. They also have cheap stethoscopes.