idle speed is 600-650 when in park or neutral. the stall happens after its warmed up and when im coming to a stop or a put in reverse and dies down to about 400-550 then it just shuts down, if i hold my foot on the brake a little and and push the throttle down it will stay running. one of my friends thought it might be the torc converter but seem to shift fine going down the road and if it is will it hurt the truck if i keep using it, and there is no mods done on the truck it is 100% stock and has 88k on it original motor trany