2005 Ford Fiesta Car turns on and off

Hi I have a 2005 ford fiesta automatic I have had this car for around 2 years now, and recently it has started having problems. First it started off as sometimes when I would turn on the car it was automatically turn off and sounds like the engine is dying. I went to my mechanic and he could not find anything wrong with it. He had the engine cleaned out to see if that was the problem, but nothing. I also had the exhaust checked out as he said that its recognising that there is too much petrol and not enough air and vice versa. I am not sure if is the ignition as the part around where the key goes in, is wobbly and you are able to move the keys in it if you try. What do you think the issue could be?

Also my car makes noises when it goes over speed bumps. My mechanic said it was the shokies however got that replaced and it still makes it. Tried putting WD40 on the bushes and coils, worked for about 30min and the noise came back. I have a feeling it could be the springs. Please advise if you can help with advice.