Audio Systems: Stereo Problems, ford focus, chassis

Question
Hi
        I drive a 2001 ford focus.I just installed my new stereo yesterday and when i turn on the engine and step on the gas it turns off and on and i checked all the wires for lose connections and i didnt find any but the stereo works perfectly when the engine is off can you help me.

Answer
You need to wire it up correctly :)
A simple, Ford-owning nooby mistake, there.
NEVER presume that a 'ground looking' wire is a ground.
What would have been easiest, would be to buy an installation kit for that car. You would not need to cut a single (Ford) wire and they have labeled wiring codes.

At this point, try running a short, dedicated ground wire to the cars' chassis for the deck ground. ;)

Lemme know if this does not help.

JM