I have pinpointed the problem as a bad spring in the TB. It seems to not have enough return tension to force the butterfly plate closed all the way, and sometimes doesn't have enough tension to even bring the rpms down. As a matter of fact, I was wondering why my gas pedal seemed so light and easy to push to the floor. As far as I know, this is the problem and I aim to fix it tonight by switching the opt. butterly plate, shaft, and screws into my old TB housing. Which, in turn, has always had an operable tension spring.