knock sensor help!!

[93gaSE3300.2007]

hi, i own a 93 Grand Am SE with a 3.3L engine, my problem is with my knock sensor.. i checked the codes thru the ALDL and all i got was code 43, which is for ESC error (w/o esc module), the old acronym for knock sensor. i'd test it but i cant find it.. its supposed to be on the right side of cylinder block, near the oil pressure switch..anyways the car gives me a sevice engine soon light for about 10-30 seconds then it goes out..so this must be intermittent.
i also have a rough idle, which is untraceable..