1999 Chevy Blazer 1999 Blazer runs rough untill it is warm

I have a 1999 Chevy Blazer, its runs rough at start up then once warm runs just fine. When you start the Blazer and press on the gas it wants to back fire and die. If i start it and let it idle for 5 or so mins it will run normal...Press the gas and off she goes. I have checked the cat (not it) I have checked the plugs wire and distributor (not it). The other thing is it will not give me a code. Any help would be great...