03 RAM Quadcab 4.7 106,000 miles. Check engine light on with the two codes above indicating EVAP system failure. As a bonus the engine RPM varies from a low of 400 to over 1000 at idle and at any speed.
At 70 MPH with the cruise on it varies from about 1800 to about 2400 RPM. Any suggestions or help would be appreciated.

 

check for a corroded hose or leak to the evap canister. the hose could be dry rotted and have a leak before you go replacing the evap canister. also check the hoses under the hood as well. dry rot and cracked hoses can cause idle problems.

 

^^^^ All of that plus the seal on the fuel cap

Welcome to the site

 

Just had the P0456 code pop up, changed the gas cap (from O'reilly's) and the code (and Check Engine Light) went away. There was also an intermitted gas cap message on the display.