[Bob Cole] “is there a “frequency analysis” filter which will give me information for EQing?”
Your ears are the best guide. It sounds like you are out of your skill zone here and the best advice I can offer is to send this to an audio pro who not only has better noise reduction but also understands the intricate balance between EQ, editing, mixing, dynamic range control and noise reduction.
STP is a useful tool but if you are already struggling with noise reduction, I don’t think it is going to save you. Multiple applications of noise reduction may help but without hearing the problem, it is hard to say. It is always a better idea to pre EQ.