I have a full size 1989 Van that has a 318 engine, 3 speed auto trans. Sometimes I do not get any voltage to the auto shut down relay, which in turn stops voltage to the coil and fuel pump. the code says 11; no IGN reference signal.(Also code 12.) Should I replace the Hall effect pick up device? A shop could not make the van fail. The starter motor always turns over. I have replaced the starter switch, the computer, the auto shut down relays and 3 other relays. Also, cleaned, tightened and cleaned connections on computer and connectors. Van usually starts, but sometimes it does not, or is hard to start. Sometimes it stalls. Coil maybe bad and shorting out voltage? Please help!