I have a 2002, 2500 ram turbo (5.9 C). When I drive the truck for 10 -15 min I start to experience a dead throttle. In other words, when I accelerate nothing changes not even the RPM gage. It does maintain the current power and RPM. I have a fuel pressure gage that shows no loss in pressure. I have 60K miles. I have changed the fuel filter, with no change. Any recommendations?