1997 GMC Suburban Starts but won't run

My 97' suburban wants to start, but won't stay running. Funny thing is that if you use some starter fluid in the air intake and it starts, you can drive just fine. If you shut it off, it won't re-start. I read it might be the security feature. I disconnected the battery, hoping it might re-set but no such luck. Changed the fuel relay but no difference. I know it's not the fuel pump because it drives fine if I can get it running. (It has new fuel filter and when driving it goes good) Any Ideas?