I have a daily drive to work in Lafayette of 50 miles one way. well i had to go to new Orleans twice this week. thats 110 miles one way. my truck ran fine going to Lafayette but the days i had to go to new Orleans my truck would not "idle down" after depressing the clutch. not every time but more times than not. any ideas? no other symptoms other than low hp with the a.c. on but then again always been like that! thanks for any help.