5000 is too much. A/C could be the evaporator which will be expensive even if you DIY. If this is still the original timing chain it does need to replaced.. as soon as possible. With the M119 its really a two man job or a trip to the shop. Exhaust is probably less serious but ontop of the other issues your looking at a substantial repair bill.

Edit - Wiring Harness

600-800 I think, depends on your source. The fellow I bought my E420 (W124) from spent 843 USD on it. Again if it hasn't been replaced you have to do it first thing.