'94 Z28 won't start cold

My 1994 Z won't startwhen the engine is cold and the ambient temp is under about 50 degrees. I can get it to start right up with starting fluid, and then she runs fine. If I try to start it later on (when it warms up a little), she fires right up. I replaced the fuel pump about a year ago. I just replaced the IAC valve, but that didn't fix it. DEFINITELY not lacking any power once she's running (LT1 is nice!). Any ideas?