[shorod]

You didn't happen to recently switch to ethanol fuel, did you? What was your fuel economy before with the A/C on?

You may want to check the Mass Air Flow (MAF) sensor for contamination and connection, make sure the intake air temperature (IAT) sensor is connected, and check the coolant temperature sensor.

Did you change all those items in an attempt to improve the fuel economy, or did your fuel economy drop after you replaced everything? If the latter, then I'd suspect that you didn't get something connected properly as a result of replacing items, and I'd start with the MAF and IAT. Also make sure that the intake air hose is tight and installed correctly. Although if the hose is not correct, you'd likely have other driveability concerns.

-Rod