Car sputters and hesitates when cold, won't start when warm

I have a 1990 olds cutlass ciera, 3.3L 6cyl that has recently begun to stall when put into gear. Until it warms up it sputters and hesitates like it's not getting fuel. After driving it a while that problem goes away but after I stop and let it sit 15 minutes or so it will not start when I get back in. If I let it sit an hour or more then it starts and runs with the same hesitation. Once it's running it runs fine until you come to a stop light or something and then it begins to sputter and stall once it has warmed up. I've replaced the spark plugs, fuel filter, and had the fuel injectors looked at. It seems to be getting worse and I'm out of ideas.

Thanks.