Troubleshooting a Chrysler Concorde doesn't have to be complicated. The first point to remember when troubleshooting a Concorde is that you need to start with the simplest possible problems first and then work your way up to the more complex problems and solutions.
Check to see if there is any liquid underneath the vehicle. This is often overlooked, but very important. Red liquid indicates a leaking transaxle. Brown or black liquid indicates a leaking oil pan reservoir. Green liquid means that you are leaking engine coolant. If the liquid appears to be just water with no smell and is clear, it is likely condensation from your air compressor/air conditioner. This is normal and will not cause any serious problems. However, any of the other liquids indicate a potentially serious problem that needs to be addressed by a mechanic.
Listen to the idle. If it is too low or "rough," you'll need to adjust the throttle cable adjustment screw clockwise to tighten the cable and normalize the throttle tension and consequently, the idle. If it is idling above 800 RPM, then you need to turn the throttle adjustment screw counterclockwise to loosen the tension on the cable and the idle speed.
Check to see if there is any colored smoke coming out of your tailpipe while you are driving. White smoke is steam and means that you are leaking coolant into the combustion chamber. This can be dangerous and cause critical engine failure due to hydro-lock (the engine tries to compress and ignite water and is unable to). If the smoke is blue, it indicates that you are burning oil. This is caused by oil blowing by the piston rings of the piston. Black smoke indicates that your engine is getting too much gasoline and is running "rich." These last two problems, while not as serious as leaking coolant into the system, still need to be addressed and fixed.
Listen for noise in the transaxle while the Concorde is shifting through gears. This indicates that there is not enough lubricant in the system. You'll need to add transmission fluid to the system, or have a mechanic service this for you.
