heres my trouble guys- just installed a new motor in my 89 gmc k1500 tbi 5.7 auto. am able to set base timing at "0" fine. reconnect wire (tan & black) and will idle and rev up great sitting in park, take it out on the road and states breaking up and backing firing. took it out for a road test with wire disconeccted, ran good. seemes like it's getting to much advance when under a load or even a small load, and wire is connected. no trouble codes! Any ideas before i pull out the rest of my hair? Has known good module in it. the one thing i did happen is that when i was reinstalling motor and was reattaching grounds, the smaller ribbon ground on the pass. side at fire wall broke the stud off when i was reattaching(what a great idea-lets put a ground right under the hoses for the heater core, that way it can rust and corrode) anway i ran another ground from the firewall up around the fuel pump fuse to the water outlet with the other grounds.