97 suburban has trouble starting

Our 97 Suburban (350 v8) takes several tries to start, it cranks but doesn't start. Originally thought it was electrical and replaced wires, cap, rotor, plugs. Have also replaced fuel filter. I can hear the fuel pump before and during cranking but as I am usually alone when trying I can't see in the thottle body to see if it is getting fuel. If I spray starter fluid into the throttle body it starts up first try. Once it is running it works great. I was reading in a Jeep forum someone with a simlar problem, it was suggested to check their crank positioning sensor. Could that be the problem here? Would it run perfect, once started, if the cps was bad? Any help would be great!!

Try checking fuel pressure with a gauge. These vortec motors are pretty touchy, and if the pressure is just a few psi low, it can't open the injector. I think it has to be at least 60 psi before the injector will open. Good luck!