hi, i am new here and hopefully someone can help me out. i have a 347(fuel injected) in my 89 mustang gt. at anywhere from 800-1000 rpm,i get this loud, high pitched whistle, almost a ringing sound. i have been a mechanic for 20 years and never heard anything like it. i have narrowed the noise down to either the throttle-body or upper intake. just for a little more info- gt-40 upper and lower intake, holley 75mm throttle-body, 30lb injectors, march ram air, egr delete, adjustable idle air bypass plate. has anyone ever had this issue???