Here's the history. Engine management light (EML)coming on when going up hill mostly or accelerating on motorway (flies down back roads by the way). Put common rail diesel cleaner into diesel. EML doesn't come on again. Driving really well with good power. Starts fine each cold morning, trouble starting at lunch time and when leaving work (engine cold), each time black smoke cloud when starts, I'm thinking the cleaner has damaged the heat/glow plugs but can't figure out why it start fine from stone cold. Today after 4 days of no EML, taking longer to start after 3 hours cool down. Car won't start at lunch time after filling with Diesel. Tried easy start and she ran on that until it cleared then stopped. EML and battery light on when turning over. Went back to car 3 hours later and she started. Drove home about 10 miles this time blue smoke coming out at gear changes. Then up hill at last mile EML back on and into limp mode, clears down hill. Anyone any ideas.