Well I was on my way home from work in the rain today and my tach started acting up. At idle it was reading zero and when I was around 3000-3500 by the feel and sound of the motor the tach was reading clear up at 5000. The needle was hopping all over the place as i drove. Has anyone experienced this? By the time I got home it was working a little better. So I am thinking it's short or something like that. I just need to know where to start on this one. I love this truck but man it has been a bad month for mantainance