Thermostat

What is your question?

My car started to over heat and the check engine light came on. I did an OB2 sensor check and a code came out. it was indicating a Problem with the "Thermostat" so I started to work on it and when I opened up the part where the Thermostat goes I saw that my car did not have a thermostat.. I just bought it in an Action. but now that I kind of fix it, It does not sound good its shaking to muck when I Revit over 2,000 RPMS.. what can I do?