Hello.

"Reset the ECU by turning off and on the red switch behind your seat, (presume you have a red switch?)"

I have done this

"Check the seating/ or swap fuel pump relay."
I will do this

"Clean fuel pump connections."
I will do this

"Replace the fuel filter."
I will do this

Must I buy an new ECU? Who can repair this?

Thank you very much.
Sven