2000 Blazer won't run

Help my blazer just died and won't start. The fuel psi is around 65, I have fire at the plugs (blue spark), I changed the crankshaft sensor, distributor cap & rotor, and the plugs. Injectors are also working, after you turn it over for a while you can pull a plug and it is wet with gas. When you go to start it, it just turns over, it won't spit,sputter or anything. Everyonce in a while it will backfire but not very often.
Computer codes are;
PO174 System too Lean(Bank 2)
PO171 System too Lean(Bank 1)
PO446 Evaporative Emission Control System Vent Control Circuit Malfunction.

Can Anyone HelP??????????????
Please
Thanks

Posible ignition control module , or spark control module . sounds like the timing is well off .Rob

Have you done a tuneup lately?

Ever changed the fuel filter?

Yes I have changed the fuel filter, I forgot to list it also. How do you check the timing on the 4.3 vortec csefi engine?

I honestly don't think it is timing, a five year old engine just doesn't jump timing without something major causing it.

Is the check engine light on now?

Sounds like the MAF sensor is on the fritz.

The check engine light did come on before it quit.
After doing some more test this is what I have found.
When you first turn the engine over checking the spark at the coil, it has a nice blue spark for several turns then little or no spark at all for a few turns then it starts to spark again. Plug a test light into the ingination module it blinks very fast like it is working. Checked the coil with a ohm meter it shows to be ok. Maybe the coil is going out?????
Or could this be the PCM?

How is the battery charge?

Is the battery dead? Could be a dead alternater drinaing the battery.

Silly question, but can you see the sparking at the coil without pulling the wire?

I have a 97 blazer with a similiar problem. If I let it sit a few days, it won't start or has a very hard time starting.

Try starting it, don't step on the gas. If it doesn't start after a few revolutions, stop, turn the key off, and try again. After a few attempts, it will start. But sometimes, when you stop cranking, and turn the ignition off, it gets a quick spark.

IT'S ALIVE
Ok just because the ohm's checks out ok on a coil and it throws a nice big blue spark dosen't mean it has enough volts to crank these newer engines. I changed the coil it started the first try. Pluged the old one back in and nothing. Pluged the new one in and it has not missed a lick.
Thanks for the input guys.

Sweet, glad to see you on the road again.