DTC P0335 and P0341

i know that these codes correspond to the crank position sensor and the cam position sensor circuits malfunctioning respectively. other symptoms include, no spark at any cylinder and no 12v input to the cam position sensor from the PCM. am i correct in diagnosing this as a bad PCM?? although these things are supposedly "highly reliable" i've seen quite a few people on these forums find that their PCM crapped the bed. i've considered changing out the $13 crank sensor but i can't get the damn thing out without possibly snapping the head off the retainer bolt because of all the rust around it and the surrounding area. any other suggestions?? by the way; this is on a 97 Sunfire with 2.2L engine/automatic tranny.