Hi, Recently the glow plug light in my car would stay on for about a minute after the car was started. At the same time, with the mornings getting colder the car has started taking a long time to start from cold. To get it started i would have to crank it 3 or 4 times at 10-20 secs a time. The car is a 1997, 160,000 miles and has had an oil and filter change. Today i changed all the glow plugs, but on a warm engine, the car started fine, but the glow plug light still stays on. Tomorrow i'll try to start it from cold to see what happens, but in the meanwhile if anyone could hint at what else to investigate i would be very greatful. thanks.