Noises problem
1997 Nissan 240SX 4 cyl Two Wheel Drive Automatic 117,00 miles

I have a 1997 Nissan 240sx. I've been having low idle problems and the check engine soon light is on. After the car has been drivin a while when coasting my idle will jump between 500rpm and 2000rpm. After a short while of this is will stale. Sometimes I can restart the car and get to my destination and sometimes it will die again right away. I have recently changed the fuel pump, fuel filter, distributer cap and rotor, plugs and wires. The fuel injectors and engine timing have been checked and are fine. I've also cleaned the throttle body. I've also left the car runnig for about a half hour with no problems until I start to drive it. I just today had a friend look at it and he thought it was the fuel relay thats been changed but I swear it is still doing the jumping idle thing. I also just had new struts put on my car and when driving home there was and extremly loud knocking or banging noise. It sounds like metal on metal. It makes me think that something is not put back correctly and and is getting continuosly knocked around. the car drives fine any idea what could be causing this? Thank you so muck for your help!!!!!!!!!!!!!!