my 1990 Legacy, we changed the head gaskets on it because it was overheating. And Now that weve put it back together it doesnt run like it did before. It stutters and eventually chokes out and dies. Im unfamiliar with Subaru engines, as this is my first. If anyone can help me with a possible problem i have, please let me know. Thanks.

Just out of curiosity, did you plug the MAF sensor back in after your finished? If this sensor is unplugged, the engine will do just what you said.

 

If all electronics check out, do a compression test to see if you did it right.

 

There is also a very involving and precise head-bolt tightening process on 2.2's that will cause problems if not done correctly... Find a Haynes manual for 90-98 Legacies for that procedure.