I've got a 98 tahoe with a 5.7. Having some starting issues but runs great once its finally starts. I just did a complete tune up plugs, wires, cap, rotor, coil, icm, fuel pump and filter. All A/C delco parts. The vats system has been disabled in the pcm with a tune. After sitting all night I have to use starting fluid to get it to start but then it starts fine on its own after that. I havn't been throwing parts at it tho. The fuel pump had been getting loud and the tune up was just planned maintenance. Now when this all started I was pretty positive about it being thats vats system. It would try and start for a second or 2 then go back to just cranking. I could see on my scanner that it was shutting the injectors down which is typical of the that stupid security system. Now I'm running out of ideas. Any help would greatly appreciated.