My cars thermostat is jumping cold/hot, not.

I need to know what engine you have. Also what have you done and what has been checked at this point?

Sounds like you may have an intake leak. Meaning the intake gasket might be leaking into the cylinder so the engine is burning the coolant not leaking it. Could be a head or head gasket too. So have the shop check it and do a chemical test before just replacing parts. The chemical test will tell you weather or not it has cumbustion gases in the radiator if it does then it is a head or head gasket, it not then it maybe an intake or intake gasket leak. This manifold is also known for the throttle body leaking coolant into the intake too. So there is your heads up hope that helps.

Well that all depends on what is found to be wrong. If its an intake leak then it should be a few hundred if its heads or head gaskets then around a thousand or more. I would not worry to much untill you have the chemical test done. Keep in mind that these intakes do have leak problems so we will see.

Good that shouldn't be so bad. Let me know how it goes. Have a great day.

Go with the bars leak tabs. They are 6 tabs that come in a package it is what GM does when its just seeping. The miss may be part of the problem and may not be so lets do the tabs first.

Was affraid it wouldn't. I still think is maybe an intake leak, it is common on those.