90ls400troyfromthebay

So I recently just bought a 90 ls400 and I had this problem of white smoke alsoafter I plugged both of the exhaust and intake lines on the manifold I started having an idle problem at low speeds to the point of where it would die tonight when I drove home from work it died twice and started back up but it seemed kinda sluggish and even would jerk while I was accelerating anyways can anyone help me out with an idea on how to fix this ? Please and thank you