Usually there is a flat braided ground from the rear of the right head to the firewall. Make sure your ECU has a good ground on it. The fuseable link should be right by the bulkhead connector going through the firewall.
Thanks. I checked grounds today, they were clean and tight, I went over them anyway. Also added the engine to firewall ground. Also checked all of the above mentioned, cleaned, re-tight etc. Then I did a testdrive, keeping close to the garage and all went well, drove a good 40 minutes.