There’s quite a few things on the main EFI fuse.
Firstly check the feed to it from the battery, there is a 15A fuse before the efi relay from the battery from memory. Check the current it is drawing. Guessing you have a multimeter or can get access to one?
You then have a feed that goes from this to the ECU, again check this, and the ECU itself.
Injectors and Coil are also powered by this, so same applies as above.
It is ground by the left hand fender, check this and re ground if necessary/for peace of mind.
The fuel pump relay feeds from the main efi relay also. Again check this and it’s grounds.
The original boost control solenoid is powered from the efi relay. Are you still using this? The other air con / icv are also powered by this.
Check all the above and you should find one of them causing the issue.