need some tech help

[Bowed]

took one of my trucks for emmissions today ( its either a 230 or a 250 6 CLY ) and it passed every thing except the idle test . here are the readings.

(HC) in PPM idle standard 250 Actual reading 885 ( FAIL )
(CO) in % idle standard 2.00 Actual reading 5.88 ( FAIL )

(HC ) in PPM loaded standard 250 Actual reading 124 ( PASS)
(CO ) in % loaded standard 1.50 Actual reading .57 ( PASS)

Is this just the wrong idle adjustment on the one barrel carb or do the figures indicate some thing more involved . Also during the test we did not know the thermostat had become stuck and by the time the test was done the truck had over heated real bad , could too hot an engine cause that bad idle reading ?? It turned out to be a real sh***y day , on the way back the truck was over heating so bad , we wound up pushing the truck the last 2 blocks just to get home . Thanks for your help .