91's, what to look for
Besides looking for the obvious stuff, intercooler, no damage, paint, tires, etc. look at the maintenance for the fuel pump, fuel injection pump, and if a manual the Getrag transmission. Those transmissions are expensive ($2500) and most failed at about 80,000 miles. I understand the replacements are much better. The fuel injection pump is about $1600.
I just sold a 91. 5 4x4 LE 5-speed manual, 3. 55 gears, and those are the three big things that needed addressing before 140,000 miles when I sold it. Mine was charcoal grey; the paint was history.