Aside from the vac modulator at trans [ techman post], I have seen a bad rear master cylinder seal fill the brake booster with fluid . It gets sucked right into the intake and smokes out the exhaust.
Rare, but worth looking at. usually have to keep adding brake fliud, but you do not know that cuz ya just bought it.
Tranny mod is usually red , but also a good possible.
Take a peek at the rear res levelon brake system and if it is down, take the hose of and see if it is dry..