Can I use an 88 2.8L wire harness in a 92 3.1L?

Will I have to rewire anything?

no. there is abs wiring in the 92, aswell as the egr being different, and a bunch of other things.

Are they things like the wipers, blower motor and engine functions?

What if I use a 2.8 computer and do not wish to use ABS?

your abs is actualy a seperate module, if you use the 88 wiring harness, you have no wiring whatsoever for the abs. also, an 88 used a mas airflow sensor aswell as the map sensor, you would have to get that sensor and add it in. you may also have issues with your speedo, 92+ used a hall effect pickup were 88 used a gear driven speedo.

you would be a lot better off finding a 92 harness and swapping it in.