When you mean dead, do you mean the car does not crank at all or does the vehicle crank and crank but just won't start? And this is the only code that has come up?
Let me know and I will see if we can get you fixed up. Thanks.
If you already replaced the ECT and the code is still coming up then there might be a possibility of a short in the circuit for the sensor. One thing that you can do if you have access to a scan tool is compare the ECT with intake air temperature. On a completely cool engine with a scan tool, the ECT should be within 3°C (5°F) of the IAT. If it isn't and the P0128 code is coming up then I would lean towards a short or an open in the ECT circuit. Like you mentioned above, I would also get that fuel pressure checked when the problem occurs and see what's going on there. Most likely since this seems intermittent, I would lean more towards something with the ECT circuit if that is the only code that is coming up. This could also be caused by a poor connection due to a connector being bad or this could be a bad connection at the PCM. I hope this helps. Please let me know if you have any other questions.