causing this to happen? lately( for about 2 months) when I start my car it either dies or idles roughly until engine gets warm then it runs fine. It also does this if it has been sitting for awhile. What part is causing this to hapen. We just had tuneup,timing belt,tranny flush,radiator flush,motor mounts,oil change done. Could the mechanic have set the idle wrong or the timing belt? Its like the car doesn't know engine is cold. Help!!!!!!!!!!
Do you know how much a collant thermostate costs or an oxygen sensor? Could I have someone put it on a diagnostic machine and would it tell me exactly what it wrong?

it could be a bad thermostat.

check coolant temp sensor could be way off