93f-150,4.9

So I just bought my 93 f-150 with the 4.9 and auto the truck runs amazing but I have one issue occasionally when I'm driving the radio will become staticky and the volume will fluctuate and when I turn the steering wheel especially when goin slow or stopped the volume will drop and the voltage gauge will drop dramatically it still runs "normal" voltage but it shouldn't drop that much when I shut the truck off and turn it back on the problem goes away I'm thinking it may be the voltage regulator or altenator but some people have said it May be a problem with the power steering pump or rack does anybody have better ideas or in depth ways of trouble shooting to solve the issue thanks