Thankfully you have a BGB though. There are actually big sections devoted to diagnostics and troubleshooting. That's where I'd personally start. It will guide you a lot better than nearly anyone can. With the rich AFRs you will need to be wanting across the circuits on the O2 sensor, MAP https://jdm-nissan-sr20-turbo-eng82680.blue-blogs.com/42025458/4age-engine-for-sale-an-overview