Car stalls when in reverse

I recently had my head worked on and decided to re do the seals on the oil pans since the engine was torn down. I also replaced timing belt and water pump. When I got all back together I now have and idle problem when in gear (atx) and stopped and also when in reverse. Could these be a vacuum leak or something up with the torque conveter / tranny?

It has stalled in reverse and also in the mornings when i put it in drive it will take a couple of seconds for the transmission to grab and start turning the wheels. I also hear a clunk when the transmission grabs.

thanks in advance.