2003 sierra 1500 won't start
 

So the other day driving to work my truck started sputtering and back firing. To avoid stalling in the middle of a turn I gave it gas and the engine lost power, stalled and rolled to a stop. The engine would crank, start and have a very rough idle till it eventually stalled. If you stepped on the gas at all it would die. In addition to that, the check engine light was already on for a large evap emissions control leak( suspect, vent valve solinoid). The check engine light had been on for a couple thousand miles with a cylinder misfire and the evap code. I ran it cause it made no difference in performance. The symptons this particular day would last five to ten seconds.

I took off the air filter and checked as many vacuum hoses as I could find. I started it and looked under the hood , no hissing and same symptoms. I tapped lightly on the fuel filter and surprisingly she ran good for about a mile and then stalled again. I tapped it three or four more times along the way and got it home. I changed the fuel filter and she ran like a champ for ten solid minutes from idle to four or five thousand rpm. I played with the pedal trying to repeat the problem. It ran so well I thought I fixed it. An hour of sitting in the driveway off, and a trip around the driveway the symptoms returned.

I read the codes and got a po445 and a po449.

One was for the purge valve solinoid and the other was the vent valve solinoid. No codes for misfire or evap leaks. I changed the vent valve solinoid and couldn't get a purge valve before the part stores closed. Im under the impression that should not cause the truck not to start.

I thought gas, so I put some in to make sure it wasn't out and to see if the gauge was wrong, no dice. I emptied the new fuel filter into a glass, no water and very little, very fine, sediment. I figure the sediment is from the rusted threads on the fuel line nuts ground into the treads of the fuel filter. I checked for fuel preasure at the fuel rails by using the ''fuel pressure check valve'', I had fuel at the rail and it squirted out so I have pressure too.
I then started looking at the ignition system. I checked the coils and wires for spark. I stuck a screwdriver in and got a spark at all 8. I checked the plugs, the gap was .06, and it had very little black grime around the bottom of the threads and they smelled like gas. I put in 8 new plugs.

Surprisingly, it won't even start. I can hear it gasping for air with the air filter off. I have spark and fuel but it won't start. Its turning over but no longer catching.

This could be altogether separate but, I noticed the park/reverse/neutral on the dash was dim. I tried to start it in reverse, no start, neutral no start. Its either a new neutral safety switch or an adjustment. Could that cause it not to run? I'm not sure.

Anyone have any ideas or see any checks I missed? I seem to have the basics in order, air, fuel and fire but now I'm lost.

Welcome to the forum.:) It sounds like you ran down the battery. When you say "it won't even start," do you mean it won't crank?