Mine is running okay-ish now but paintwork is awful. Been fighting an idle issue for a couple of years.
Misfire over 3k might be your MAF.
Is the 4WS light on on the dash, or just there? If it’s on, then your power steering is likely low. If it’s just there, then yes, these cars came with 4WS, but many owners delete the rear steering due to leaks.
For the fuel pump, I think due to how old these cars are, it’s best to try and keep them as original as possible, so try fixing the wiring issue first before hotwiring it. There’s lots of threads on the pros and cons of doing the hotwire.
In terms of resources, you should bookmark these:
Genuine Japanese Car Part Imports - Amayama - parts directly from Japan
https://www.stealth316.com/ - loads of great guides and info
Mitsubishi 3000GT/GTO & Dodge Stealth Wiki - loads of great guides and info
https://mitsubishi-asa.com/ - parts catalogue software for your VIN
https://www.evilempireperformance.co.uk/ - great online store for GTO bits
https://www.euro3sperformance.com/ - great online store for GTO bits
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