Brake Disc Rotor problems of the 2002 Mitsubishi Diamante

I have a 2002 Mitsubishi Diamante. I have kept regular maintenance. I am submitting this form because of a heater core issue I am having. However I have had the following problems with this car. All these problems seem to be recurring problems that happen to many people with this model. At least that is what I find when I search the issues on the internet 1- vibration in steering wheel --this happened multiple times after taking car back to dealer-it appears there is a known issue with the rotors in this car. After having the rotors cut twice by the dealer with no long lasting success. I had to have the brakes and rotors replaced by a mechanic ( car had less the 10,000 miles when issue started happening) 2- rusted muffler--not sure if this issue happens often but after 23,000 miles I had to have my muffler replaced because there was a hole rusted through the top of it-I was told this could happen for not using the car very much in the winter time( road salt can cause the rust) 3- heater core- I know have a heater core problem in this car. I have antifreeze leaking in passenger compartment. I have an antifreeze smell in the cabin of the car. My windows fog and the defroster will not clear the windshield ( makes it worse). I am low in antifreeze because of this. My service engine light has now come on and I am told this can be caused by leaking antifreeze onto the computer which is positioned under the heater core. This issue is widely reported on the internet in many forums and seems everybody with a Diamante will eventually have this problem. I am being told this repair can cost over 1,000 dollars 4-I have had to replace 3 sensors in the engine 2 egr and 1 idle sender (cost around 1,500 dollars). This may or may not be because of the heater core issues causing the cars computer to fail.

January 12, 2005 one cold morning I noticed that the reverse gear did not go in as fast as it should it took like 1 minute to go into gear, when cold it would jolt before advancing in drive. Took it to the dealer, they did not find anything, so I picked up that same afternoon, next morning same problem. I took the car back on Jan 19, left it over night and they found it took a couple of minutes to go into gear, therefore, they decided to look at the transmission, the car has been at the dealer since 1/20 thru 2/7, after several discussions they have told me it is the heating core dripping on top of the computer damaging the sensors, today 2/8 the car would not go into gear at all. I have had grease with the seat belts, they had to be changed at 3600 miles, the tires (eagle) had to be replaced at 18,000mies, the brakes starting acting up at 6000 miles, the steering started vibrating at 12,000 miles. Bottom line this car is a mess, sucks and Mitsubishi does not want to be responsible for any of those problems, this is a big lemon!.