Chevy lumina 1993 3.4 6cyl. car will start but only run for about 20 to 30 secoonds then it will die.

Clean the Throttle Body and MAF. The Throttle Body is carboned up and is not closing fully.

https://www.google.com/search?q=1999+chevy+lumina+clean+throttle+body

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Save Your Money. The Lumina is one of many GM throw away cars. Scrap it. You can buy a running car cheaper than fixing the Lumina. Just don't buy another GM product.

check your EGR valve

Sounds like low fuel pressure. Check your fuel pressure. If you have the 3.1 liter engine and just turn the key to the "on" position you should have around 41 - 47 PSI. When running it should have about 31 - 44 PSI. If you have the 2.5 liter engine you should have 26 - 32 PSI of pressure when running. I hope this helps and good luck.

have you changed your fuel filter?

check idle air control motor or could simply be throttle plate very dirty

replace the ignition control module.

just look above the brake padel, in front under the dash it have two bolt,10 or12 mm. remove bolt take
out wire harness then reverse watt you did then you
put it back easy to do about 20,30 mi.

Try replacing the throttle position sensor. I had the same problem in my truck. It would start and run for a bit but as soon as you let off of the pedal, it would die. Try it and see if it works.

yes this could be the problem. the pcm is getting the wrong info and shutting engine down.