Good stuff guys and you are right that there is an issue with the electrical connection between the rear subframe and the main frame but only when you're putting 100cold cranking amps through it.The ECM is probably only pulling 300 milli amps and I have gone round the various consumers and measured the voltage drop on both the power and negative sides to see if there is a bad connection between them and the battery when they are powered up and the worst is less than half a volt .34nineteen might be right as both coils are similarly affected and that's getting a bit coincidental for me as the only common thing on the two coils is the power supply ,which is fine ,and the ECM. Separate spark plugs , HT leads , secondary windings and primary windings but the same weird primary voltage pattern and that is controlled by the ECM.
M