POSSIBLE CAUSES

-EVAP Canister
-Wiring Harness Intermittent
-EVAP Purge Hose (Canister to Fuel Tank)
-EVAP Purge Hose (Solenoid to Canister)
-EVAP Purge Solenoid Vacuum Supply
-EVAP Purge Solenoid (Leaky/Stuck Open)
-EVAP Purge Solenoid (Stuck Closed)

Hope this helps

1987 D-100 SWB, 390hp/360ci Mopar Performance Crate, Built 998 trans, 9.25 axle with sure-grip and 3.92's - 3960#'s with driver 13.83 @ 96.36 1.98 60 ft 2003 Dodge Ram 2500 HD 5.7ltr HEMI!!!