My 1995 safari (4.3L V6) with 274,000 miles just failed the emissions test for hydrocarbons. The tester said that the idle appears to be too advanced. I need to check the timing but I can't get by square one because I can't find the single Tan/Blk wire that disconnects the ECM and creates base idle. I have looked on the passenger side firewall, and in the passenger side foot well around the ECM. It has got to be here somewhere... aaarrrgghhh!