occasional rough idle and stumble

[03blackburb]

Did some driving around today and got stuck in the "Austin Parking lot" traffic. My water temp went up to about 227 on the digital so I turned both fans on (manual switch installed for both fans) and the temp came right down. Did this several times. The temp was going down to about 205 and then after a while of very slow driving she started to idle roughly and had a stumble on take off. Made a couple of stops and afterward she drove fine with no rough idle and no stumble. Coolant level is fine, no leaks. The radiator was flushed little over a year ago and temps while driving run about 198, but in stopped bumper to pumer traffic temps do climb to high 220's but the fans bring it right down. BTW she is a '94. Any ideas?

[hotrod_chevyz]

165-180 thermostat and fans. You might check the flow and see if you have buildup inside the radiator.

[Schrade]

Could be too much exhaust gettin' recycled through the intake, which by design is to keep combustion temps from gettin' too high.

How was acceleration from a stop, BEFORE you turned the fans on to cool the water?