I recently bought a 1987 xj6 vanden plas. I replaced the entire cooling system and it ran ok but didn't have much power. Then all of a sudden while I was driving it it seemed to bog down and want to die. It would stay running but basically only idle down the road. All the gauges seemed fine so I'm not sure where to start. Any help would be great! I was leaning toward a fuel problem, but not real sure.