anyone change one of these on a hyundai or kia? i got a code p0087 low fuel system/rail pressure. the car idles fine but when under load/acceleration it stumbles. everything i read indicates it is this pump. i don't trust the local dealership and my mechanic who i use for things i won't do like a head gasket --and always does a good job, says they haven't had to change one before. that doesn't make me feel very good. thinking about doing it myself and was wondering if anyone has changed one--- i've changed regular fuel pumps before but not one of these--cam driven on the head--new to me