Audio Systems: 2003 jeep liberty stereo, infinity speakers, side speakers

Question
i have a factory installed stereo in my 2003 jeep liberty. it has infinity speakers with an amp in the stereo and an amp in the front speakers. the left side speakers have stopped working but every now and then they come on. i was told it was probably the amp in the stereo but when i replaced the stereo the left speakers still did not work. now i'm told it is probably the amp in the front speaker. i would like your imput on this as this is becoming an expensive fix. thank you so much

Answer
hi
have you been in a car accident or was there any major repair done in this vehicle  there is a plug in the door that is very hard to get or plug back  audio works but sometimes turn on or off
infinity amplifiers are very good i never seen one that didn't work or with that problem
sorry i can not help more