What's up with my 1992 LS 400? Several weeks ago I noticed my brake pedal seemed substatially stiffer upon startup. When I tried reversing the car from its parking space, it felt as though it was rolling on four flats, or like the car was trying to power through a great deal of resistance. The problem eventually disappeared within a minute that day, but has since resurfaced to a greater degree recently. It feels as though the car's engine is now experiencing an unusually heightened amount of strain when I drive it [seldomly] , in addition to producing that unmistakable stench of scorched brake pads. Both these symptoms seem attributable to one or more seized brake calipers, but i'm not completely sure. Why, then, the stiff brake pedal? Based on these telltales, can anyone help identify the problem based, perhaps, from personal experience?