speakers popping and cutting out

My system at this time is a stock am/fm/cd player, mid-line variety, with 6 speakers..it is installed in a 1999 Chrysler(Dodge) Intrepid. It has a factory amp in it.

My problem is, first I lost all sound on the left, then the right fronts both went out, then they kicked back on...while all this was happening, we noticed that when ever the turn signal or brkes were applied, the left rear speaker would make a popping sound. I have been told it could be a ground problem, its just I cannot find where the ground for the HU is on the car. But i cannot see how a poor ground would cut out a entire side?? But still cause a pop sound? Any ideas on what to test and how, or should I just run it in to a shop and have them take a rip at it?

                                                                                              Mike D aka Ice-cold

starting to think its the amp...will try out a different one to see whats going on...Thanks for your time

Its all stock..just recently we discovered that the car was in a accident and the air bags had blown, also while looking for the ground, it looks like there was a remote starter installed but someone has removed it and left all the plugs and harness behind.

Am thinking there could be something loose or bare somewhere that I have not been able to find as of yet.

There is a steady buzz coming from the speakers that is not rpm based..so I am thinking the amp is pooched or there is a major groound problem here.

                                                  Mike D  aka Ice_cold

Going with a aftermarket set.....Like the stock look but its to much hassle. Will be running a small system for now...have one prob ...the HU is from my truck,which was totalled, my buddy pulled the deck, but forgot the wiring harness and plug for it and the face plate. The unit is a Pioneer DEH P8250. Any plave in Canada that I can find it cheap? Or am I going to have to get hold of Pioneer?

Thanks for the insight...Mike D aka Ice_cold