acoustic drum recording problem

I am using a Presonus FSP to record real drums with 8 mikes. With the bass drum, I get a flam sound, like ful-lub. It is not on the soloed BD track, but comes when the High Hat, Cowbell or overhead tracks are on. I read this article on noise gating and other factors (http://gorangrooves.com/drums/secret-to-producing-drum-tracks-from-the-raw-recording.html) which seemed very useful, but I can’t get rid of this sloppy BD sound. I tried low pass filters and some gating on the HH or CB track and just played either with the BD track but I can’t get rid of the flammy sound. I spent so many hours getting nowhere and so I can’t even get started to have a decent drum sound. Any ideas?