Stalls out

I have a 91 ford tempo. I just replaced a piston and all the compression rings. The car was running ok for a while but minus its pick up and get up and go. Now the car stalls out everytime I shift it into gear. Does anybody have any idea how to fix the problem or what is causeing the car to stall?

Sincerely,
Kevin

Any other symptoms? This may not be related to you recent repairs.

auto or manual?

it is automatic. And I don't believe there are any other problem or symptoms. The only thing that I remember is when I was driving it right after replaceing the piston, if it stalled I had to fight to start it and once it did start it blew out a lot of black smoke from the exhaust.

Sincerely,
Kevin

Piston rings that are not sealing properly can produce these symptoms. Its possible that the rings are leaking compression because the cylinder walls were not honed when the rings went in or they were too badly worn or damaged.
Try a compression test and a cylinder leak-down test. If everything is okay, then something was not hooked up properly when the engine was installed:
-incorrect camshaft timing or ignition timing
-the exhaust might be plugged, (especially if the catalytic converter has overheated and melted internally.