Thanks. Already begun replacing the wires between connectors. The connectors all seems OK & no need to replace. Started on the Fuel Injection & the wires are defintely BAD. Then found below this harness is the Coil Packs Harness which is also very BAD (touching), will take this later. One thing at a time.

I change the wirings using any color I can get a hold on, rather than its original color.

Can some 1 confirm its fine to use bigger gauge or mm wiring replacement?

Finally on one of connectors, it has 4 wiring whose insulation are gone. Is there a plastic (plus shape) to slot betweem them , like a divider, after I heatshrink these wires?