I just got a used 04 A4. I’m not a mechanic of any type just trying to get my used car fixed. Here is the issue when the car sits it starts fine but when I idle rpm bounce. If I drive it and turn it off and run into a store if I try to start it it won’t turn over. Not every time but 2 out of 5. Also when I do get it to start the rpms bounce. And epc light comes on. I don’t know much about cars so please forgiving my lack of knowledge so from 1 to the second mark and sounds like it is going to die I went to autozone and no issue with battery or alternator or starter. Not an oil issue and supposedly fuel pump replaced (what I was told) it’s old and I was able to buy from a used car lot for 2k (knowing I probably have to put more into) but I have no idea what to look for or have fixed ect ect. Please help if you can.