Here is checklist:
1) Coolant level in the radiator
2) Cleaness of radiator from the engine side (mud, dust)... You may try to apply some air from air compressor from outside and see if there dirt cloud inside
3) Fan clutch: check on the cold engine and hot engine
4) Radiator cap: cheap, so may try to replace
5) Thermostat
2001 Isuzu VehiCROSS (build in progress): 4JX1/A340/part time, 2" body lift, front Aisin hubs, rear Aussie Locker, 4.56 gears, OEM rear sway bar disconnect, AirFlow snorkel, cabin air filter
1980 Jeep Cherokee (assembling): 1.5" body lift, TBI, HEI
1987 AMC Eagle: stock