Hi I have a 1998 k2500 Cheyenne with about 305000 miles. It have the 5.7L v8. The issue I am having is that the truck has low oil pressure and idle at a stop. The pressure and idle is fine when you first start the truck but as you go you can the oil pressure drop. It usally drops to around 20 while driving and about 4-7 at stops. this idle usually goes to around 700ish rpms. I've heard that 700 rpm is normal idle but I am not sure. It has recently started doing it in park too.