Ignition timing

Further, ignition timing I have not had it scanned and there is no check engine light on. Sorry cannot add anything else, everybody says it is too old to know anything about it. Sure hope you gentlemen can help me. Many thanks.

This engine is three litre with distributor mounted TFI module had system scanned and no codes and no sensor problems when spout connector is disconnected it goes to base timing of ten degrees BTDC when spout connector is installed timing retards about two inches past timing tab and just stays there no matter what yet scan tool shows 30 to 32 degrees advance but engine is showing retard with timing light also checked voltage with ac volt meter and it shows six volts with engine running a Ford service information I have says if this voltage is between 3.5 and * volts replace ECM, does this make sense, can the ecm retard timing like I have described, with it running this way fuel mileage is terrible but no driveability problems except power is down slightly. There is nothing wrong with timing chain or distributor gear as engine vacuum is almost 20 ins at idle and runs like a dream except for terrible fuel mileage