Cooling issue, new to troopers, please help!

I just bought a trooper 93 model, with 190xxx miles on it. 4wheel drive everything works, but it overheats when sitting idle with air on very long at all, say 10mins and it is redline. But if we drive through town or on highway we can blast the air with no problem. I just spent two days replacing the cooling hoses and getting the oh so fun oil filter adapter off so I could replace the broken copper line , well we brazed it so it isn't every going to come off again, it appeared to have been pressed in from the factory and not one parts store could even order the oil filter adapter. Said it was a dealer only item, It was spraying coolant out, but it isn't anymore. . anyway, i wondered if this is something you think would be caused by the buildup mentioned ina previous post, or if i just can't run air while idle in these 3.2 dohc troopers. Thanks agian! Any common problems with these i need to address will be greatly appreciated. I have only one of about 3 in my town, no one knows jack about them. Thank you!

This might just be an old & tired radiator w/ the aluminum tubes plugged with junk from 11yrs of service. I've seen older radiators look good, but they are not. Be carefull. If you have an AT, you are overheating the ATF everytime it runs hot on you. 4L30E's wont last long like that.
G/luck
Joel

another vote for a new radiator.

radiator.com

open your radiator look inspect the cap for a damaged seal and also chek the inside of the radiator where the cap seal sits it may be deteriorated.
I have the same problem with my own trooper but I am not going to pay $600 for a radiator