Help not running right

[LEMHEAD16]

So I parked my car the other night and everything was running fine. Get up the next morning to go to work and car won't run right. It starts just fine but after about 15-20 seconds it starts to get really lean and won't run and eventually dies. If i put it in gear it dies as soon as I engage the clutch. IT doesn't do it all the time though. If I cycle the ignition a few times it will run fine for a few mintues but then when I am driving it goes very lean and then it won't respond to the gas. It just bogs down when I touch the gas and then when I come to a stop it dies. TPS and MAF voltages seem to be fine but I do occasionally gt code 12 which is MAF voltage high or low. I can't figure it out! Anyone have any ideas?

[rotorimp]

Sounds like MAF--is your engine warmed up/closed loop when this happens? Do you know the temp. when this happens?

[LEMHEAD16]

IT seems that when the engine warms up it runs a little better still not good but it will stay running.