Why is my 2000 Ford Mustang Overheating?

I have a 2000 Ford Mustang v6 3.8L Base. I will start describing what happens when you start the car: The car shakes and you can hear kicking/popping noises from the mufflers and in the front of the engine. When you start to drive, it shakes and kicks struggling to drive for several miles. When it reaches operating temperature it seems to run normal, but then it overheats really quickly. This always happens in the city (at red lights) but it seems to run normal on the freeway. I have replaced the thermostat, radiator and radiator cap. Recently I changed the Secondary Air Injection Pump from the junk yard. This last time it overheated, it spit out liquid and there was so much pressure built up in the hoses (the pressure never goes away even after the car has been sitting for days). Also the coolant always turns a little orange. I've flushed the system before because it was deep brown. Please help, no mechanic wants to work on it.

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