My guess would be a marginally performing power relay. I don't have a diagram for your model so I can't suggest a particular relay. My 1999 has four power relays if I remember correctly ... they offer a bit of inherent delay as the battery is connected. Also they provide an easy way to segregate the electrical system during certain trouble shooting procedures. .... but if the system voltage drops a bit, such as at engine idle, they sometimes barely stay "up".