my 1999 tahoe z71 died the other day and had to have it towed. I have run though some diag. but im running out of things to check. It is a no start. All plugs/wires checked. spark at all. fuel pressure is 60 psi checked and does not leak down. It will not even start with starting fluid. i don't know what check next. I really thought it would least start with the starting fluid, id imagine since i have spark on all 8 plugs, that would kind of eliminate ignition. Dist. cap, wires, rotors plugs are all 6 month old. It ran great then just died. Turns over fine just nothing. What am i missing? thanks