BMW Repair: You were right!, loose components, ball joints

Question
Hey Rahim, out of curiosity I called a nearby BMW dealership and found out you were right, it is my brake pads and luckily enough for me when I purchased the car it came with brand new brake pads! I can easily change those in my shop class so thank you very much! As far as the rattling, I talked to my shop teacher and Josh and they both said it could be faulty spark plugs and wires. Now I know it could be a great number of things, but does that make sense? because I put my car on a lift at school and checked for any loose components and found none. The other thing I noticed was once my car was "warmed up", the noise went away. I only hear the noise every once in a while after it being either in the cold or sitting a while. My car also, when started after a while bobbles up and down from 1300 RPMs to 800 RPMs until it finally stabilizes at around 1000RPMs or less. I am hoping this isn't a fuel injection problem of any sort and it is just the spark plugs and wires. Regardless I want to be told the correct information as much as it may hurt so I can fix it. Now I understand you obviously can't see or inspect my car so I will understand if you aren't quite sure. But!!!!! If you could dish out some possible reasons that would be great and thank you for respongding so quickly!

                                    Sincerely,
                                        Patrick

Answer
Be carefully removing the wire off of the brake pad.(If it has one)  Once it breaks you have to change the whole thing.  Take your time with it.  If the catalyitic converter is ratling you will not hear it by shaking it.  The car has to be on the lift running and you have to be underneith the car listening for it.  Take a long thick pry bar and put it in between the ball joints and bushings and jently pry and look for movements.  Grab the top and the bottom of each wheel (12 o'clock and 6 o'clock) and try to move it in an up and down motion and check for movement.  Then do the same but this time at the 3 o'clock and 9 o'clock positions.  Check the heat shields around the exhaust and catalytic converter.  Those tend to make a ratteling sound at certin rpms.  But not constantely.  Spark plugs and wires don't make a ratteling sound.  They make your car run rough when bad.  One more thing, You can check your valves for adjustment.  you need a feeler gauge for this.  if out of adjustment then adjust.  Loose valves or out of adjustment valves will make a ratteling sound.  Ask you shop teacher more on that one.  Also get the haynes manual for your car for valve clearence specs and etc... If you are planning on keeping the car for a while, make the $12 investment.  It saves you a lot of headache in the long run.  As far as the rpms jumping up and down, be sure the car has spark plug wires and not coil packs.  Change the plugs with bosch platnium plugs.. Not the 4 prong crap and all of that stuff.  Just the regular bosch platnium plugs.  All those high tech plugs make your car idle rough if at all.  Change the wires if it has with either bosch wires or dealer wires which will either be bosch or ngk.  remember it's a european car so use european parts.  while at it change the fuel filter with a bosch filter and air filter as well.  if it has coil packs then check the coil packs and make sure they are getting power to them and they are putting out spark.  And last but not least, try and stay away from the after market stuff.  Good luck and let me know how it turns out.