Do you have the Check Engine Light on? If so get the code scanned. That should give you a place to start looking. Some of the likely causes are low fuel pressure due to a bad fuel pump or a severely plugged fuel filter. A severely clogged air filter or air intake restriction can also cause those symptoms.
BMW is a luxurious car, hence its repair, maintenance and its parts are expensive as well. But the repairing cost totally depends whether you take your BMW to an independent shop or any dealership service for repair. The cost of repair will be high at dealership than an independent local auto shop. And also repairing cost depends on the area you live in.
Contact Eurobahn BMW MINI Mercedes-Benz Audi, a reputed dealership shop providing repair and maintenance cost at a reasonable price.
First suggestion, ensure the AC is properly charged... the AC system is very picky... so check belts pulleys and AC charge first... if the AC is healthy and this issue is still present... you have two possible solutions...1. heater control box in dash behind the radio...Expensive part $450+ and lots of labor to pull dash apart... or 2. the heater control valve in the engine bay... $130 part you can do IF you take your time
wether it's worth the cost of repair is something only you can decide, what is the mileage and condition of vehicle ? have you had the OBD codes read to see if there is a code to help with diagnosing the problem ?
Thermal issue is shutting down amps till temps moderate. You must be driving your system too hard. And check out your tone control settings especially the bass. Every 3 db boost forces amp to double power at that frequency so if you are already blasting at 100 watts, a 3 db boost will compel amp to put out 200 watts, etc. Very easy to overdrive and overheat amp. You might want to try blowing air over output stages to improve cooling at high volume levels.
You are lucky that you have good protection circuits - otherwise by now you would have blown the output stages.
The fact that you were able to repeatedly restart the engine after it shut down indicates that the battery was not totally dead and therefore the alternator is most likely to be OK. First thing I would do is take take it to have the diagnostic trouble codes read (Autozone used to do this sort of thing for free)
It is hard to be sure without checking, BMW changed from the M52B28 engine to the M52B28TU engine around that time. Enter the last 7 numbers of the VIN here to verify: http://www.bimmer.workFind out more about the M52 engines here: https://en.wikipedia.org/wiki/BMW_M52I recommend that you pursue your BMW questions at Bimmerforums.com. It's free and has been a fantastic resource for me over the years. Bimmerfest.com is also free and another excellent BMW resource.
You can replace the old radio and cassette player with a new modern aftermarket dvd player gps navigation unit like this.
Car DVD BMW E46 Navigation System E46 DVD GPS Navi
It's with more features except navigation system, USB, iPod, AUX, SD, DVD player, rear view camera video input, and it's touch screen, easy operation.
to access the windscreen bottle, you have to take off the front wheel, wheelarch and dicconnect filler tube. Using 10 mm socket take off one bolt holding the bottle. To reinstall take off side indicator to make it easy for you.
for E90 model it is normal to have leak when the bottle is full. the water is coming out from breather on top of bottle. but if the fluid is complately drain, then there's something wrong with it.
there should be 2 lines on the dipstick one near the bottom and one about an inch above it. the bottom line is the minimum level and the upper is the max level.
Power steering systems are usually either electric or hydraulic, is there a puddle of oily stuff under the car or signs of it around the engine bay? Look for a cap under the bonnet (hood) with a steering wheel symbol on and check the fluid level, if topping it up fixes it then check carefully for leaks. If you can't find either of these check for a blown fuse or loose conection.