Take all the EFI components from your '86 and use them on the '91 engine. Nearly everything on the EFI system is slightly different on the two. Almost all the connectors are different, the injectors are different, TPS, knock sensor, cold start injector, and nearly everything else that has wires going to it will have a different connector than your '86. There's a lot of minor varations among various year 22RE EFI systems. It's best if you keep it all one year. Else you will run into problems.
Just swap all of it from your '86 and be done with it. Simple.
