new main relay, continuity good from relay to ecu, and from ecu to ground, and from relay to fuses. thermostat ground clean and tight. what else should I check?

 

Might be the main capacitor in the ECU. If it smells like fish inside the ECU when it is powered up replace it immediately.

 

Have you checked the continuity/connections between the main relay and the fuel pump?

 

Try to Run a ground from fuel pump to body had same issue, I was being lazy that day and din't want to look for a bad ground so i just bypassed it to a new one
worked flawlessly been driving for over a year now like this