Motor noise in stereo

I have a 2003 Mach I Mustang. I have motor noise in stereo system. The radio can be off and I can crank the car and stereo will have some noise in it for a few seconds and quit. I turn the radio on sometimes and the motor noise starts. It will increase when the motor speeds up. I can switch the car off and later start it up again and it may not have the noise. The radio has been replaced, one amp has been replaced, the alternator and some electrical ignition parts. It still has the noise. I asked a stereo installer and he told me the noise should not be heard when the radio is off and I start my car. He also told me it could be a bad ground. He said there was a remote between the radio and amp also one between the ignition switch and battery that may be bad. He also said the ignition switch may be he problem. I thought about replacing the wiring harness. What are your suggestions?

Do you have some sort of aftermarket ignition?

Or ignition wires?

No noise suppressor between the stereo and the ignition? 2003.

Did you add anything to your car by your seft?Do you know if you do not check with the FORD deal befor you add any parts to your car can make sounds to your radio,even with a turn singles on!Manual tells you clearly that you should contack the dealer befor you do anything to your car!Buy away,"REMMBER THIS!PEOPEL GET KILLED BY GETTING SHOCK UNDER THE HOOD OF ANY CARS!ASK YOUR NEARNESS HOSPITAL!Take you car to a FORD deal,and spend about $2,000.00 to get it fix.

whew- - -somebody has been hanging around car exhaust too long!

Lackies asleep. Too many trolls here/