When I start up my car there is a heavy rattling noise coming from the front end.
When I have my foot on the break and waiting at a street light, I hear a loud sound like
the engine is working harder than it should. That sound goes on for about 20 seconds then
gets much quieter for a while. If I am still at a stand still with my foot on the break for 20-30 seconds more
it starts getting louder again.

I haven't had much of any issues with this car since I bought it. Please let me know what you think the problem is.
I do not have much money for repairs and want to know what Im getting myself into if I go to a mechanic.

Thanks,

Doug