mine does the same, you check that idle screw? In the morning mine is about 900 and after it heats up it gets and stays around 1100-1200. I think its just when the idle screw heats up it moves around and "adjusts itself" correct me if Im wrong. Also when the fan goes on and off your rpms should vary up and down 500-600 unless you dont have AC like me
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05 Srt4
Agp 3147 w/supporting mods
97 Mx-5
T28, hks man, ebay int/pipes, rfl bov, xtd 6 puck, 3" magnaflow, msd timing box,