you have 2 choices
keep the car and keep dumping money in there, all the while being miserable because your MSP is running like crap and you have to go back and forth and back and forth to the dealership to deal with this.
or cut the losses now, sell the car and eat the depreciation hit, and be happier with a new and smooth running car.
don't let money hold you down, do what will make you happy.