Rough idle on a 2005 Chevy Express 1500 4.3 V-6 on 2005 Chevrolet Express 1500

Problem with the Chevrolet Express 2005 Express. Rough idle on a 2005 Chevy Express 1500 4.3 V-6. At cold start everything runs great until I shut it off and wait 10 minutes then when I restart it runs badly coughing and sputtering and almost stalls out. I can nurse it along for about 5 minutes and then it clears up and runs fine. I was getting a PO430 so I replaced the cat on bank 2 but that solved nothing except I no longer get the PO430 code. Now I am getting a PO300. The strangest thing is that it clears up after about 5 minutes and runs fine. However, the other day I left it idling for about 10 minutes and it started its misfire problem again but only worse. It took about 20 minutes to get it to clear up that time. I took it to a local mechanic shop and they are stumped. Thank you in advance for any suggestions!

by in Richmond, TX on June 24, 2011
1 answer 1 comment
ANSWER by on June 25, 2011
Any code lite on? Autozone will read em for free....Chang air filter also
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COMMENT by on June 25, 2011
I am getting a PO300