Rough idle at start up
 

Thanks for adding me. I'm a new HHR owner! I recently got a 2007 HHR back on the road. It had been off the road since 2009. It has 12500 miles on it.
On the way to the gas station it ran out of gas. After putting 5 gallons in it started but ran rough. After sitting and running a while it will clear up and run smooth. When you shut it off and wait a few minutes, it will start and run rough again. The CEL is on so I had it read and received these codes, P0102, P0300, P0101.
If I take the air box loose from tube that runs to the the throttle body it will smooth out. Should I clean the MAF sensor with the special cleaner? Thanks for the help!

Welcome to the site, yes clean the MAF sensor with the correct spray cleaner, install the hose correctly.

Check for mouse nests in the air cleaner while you are changing the air filter!
Check the MAF connector.
You probably have crap in the 7 year old gasoline.
The p0101-2 means the MAF wires are funky. Check the connector, wires and fuse 33 under hood.
Also, oddly enough a bad ground connection to the MAP sensor can be the culprit.

Thanks! I will check that.