I Broke 2 valves on my Rio and so i had all of them replaced and the head cleaned and the valves ground and seated we pu the car back together and every thing appears to be fine. the car runs great when cold but when the thermostat opens it bogs way down and won't run good at all. the check engine is on and i had it tested at the local shop and the code that came up was P1166 which is an undocumented code so now i don't now what else to do.
i could really use some help please.

thank you
Rory