Car problems which is giving me a headache help please?

[rashawn]

Ok i have a 2000 galant that need alot of work on it.First what will cause my motor mount that is located in the back to bust, I replaced all four just 9 months ago.. Also i noticed that when I start my car its acts like it wants to cut off and then the idle goes up not too high and it runs normally, can that be a sign that my O2 sensor is going bad? I dont need a tune up i got one when I replaced the mounts