2004 tahoe cooling (not)

I have replaced the thermostat , fan clutch , rad cap , fluid , hose out the rad. and it still wants to overheat at idle. The temp outside will be 95 with the engine temp reading 220. I have hooked a computer to it and the computer will read about 10 higher than the gauge. I am running green coolant in it and it has 44000 miles .The warranty went out and I do not know what eles to try. When driving it cools down to 190 but at idle it get hot and when towing atv it gets hot in tow haul. Please help!!!! I cannot find and service bullentions on this.

Make sure the radiator fins are clean. Are you missing any plastic shrouds around the fan or radiator. I had a customer who put his fan on backwards. It ran fine at highway speed but would overheat at idle.

Either your not pulling enough air through the rad at idle or your not flowing enough coolant at idle.

Did you use a factory t-stat? or some mickey mouse crap from autozone?

Given you used an OEM t-stat there are a few things you need to test.

Are you missing any fan blades? Is it pushing air toward the motor or toward the rad?

As the engine heats up wait for the t-stat to open and feel the upper and lower hoses. The lower hose should be cooler than the upper. Can you feel it gurgling coolant throuh when the T-stat opens?

Its possible your water pump is not flowing coolant at lower RPM.

Fan blows to motor. Used AC Delco t-stat but autozone fan clucht. It stays ingauged more than the stock one did. I did see somewhere about putting a 1/8 inch hole on the otherside of the t-stat. What will that do ? I am going to check the temp across the rad. and the tanks to look for internal blockage. I did lean the rad. back tonight and wash out the ac condencer. There were a lot of bugs and dirt that came out. This I did not do the other night , as I should have. After test drive the fan clutch sounded like it was supposed to. Engagded at the start up then got quiet even while driving I could not hear it. Before it sounded like a JET. I will test it at idle in the heat tomorrow. It is pose to be around 100. Hope that was all it was.