Factory vacuum line is hard plastic, very susceptible to damage. Runs from HVAC mode switch, under console, through ECU compartment, through a grommet in driver's pontoon, across back of engine compartment, to heater core shutoff valve. Replaced mine with traditional rubber vacuum line. Big line to mode switch also hard plastic, very susceptible to damage. That was my final vacuum leak. See pic in #5939's album if curious what happens to plugs when that line cracks. Replaced with heavy duty 1/4" fuel hose. Line takes off from vacuum canister inside driver pontoon (access through charcoal canister panel). Bill Robertson #5939 >--- In dmcnews@xxxxxxxxxxxxxxx, doctorDHD@xxxx wrote: > Today I felt very adventurous so I decided to replace the auxiliary air tube O-ring, hoping it would solve my fast and irregular idle problem. (The tube seemed to be flapping in the breeze and the idle speed regulator was not screwed to anything.)