Please help- shelving eq doubling the volume in my clips!
 

I'm working with Vegas and Sound Forge and use their paragraphic eq to roll off a lot of noise below 100Hz and above 12,000Hz. I just noticed that applying this causes clips with plosive sounds to double or more in their plosive parts. Tried other eqs to do the same sort of thing but the result is the same.
I don't understand as I thought this would only affect these very high and very low frequencies and if anything just make them more quiet. Of course this comes at the worst time as I'm trying to get a new audio edit for a screening and I have to have the edit done by 8pm tonight.
Anyway, either something is wrong or there's more to know about this seemingly simple act than I thought.
Thanks ahead of time for any help!