How do I eliminate the interferences of the engine static when listening to AM radio in my Ford Windstar 2002?

It sounds like your dealer may have disconnected a ground strap somewhere. Check for a bare braided copper strap running from the engine to the firewall or frame. You may need to filter the power going to the radio. Radio Shack should be able to provide a B+ filter for that. That should help with the blinker noise. The engine noise is usually controlled with resistor spark plugs or resistor plug wires. If you haven't changed either of those then I'd still be looking for a bad ground someplace. You'd possibly save a lot of time and grief if you took it to a car stereo installer and had them look at it.