On two occasions, at the bottom of a 1/4 to 1/2 mile fairly steep grade, the car started billowing blue smoke and was running very rough. The first time the car was shut off and towed home after finding that it had lost a quart of oil in about 15 miles. I pulled the injectors and found obvious oil in the first 2 cylinders. I did a compression test and came up with readings from 520 to 580, with the oily cylinders being higher. Since the car also blows a large cloud of smoke starting cold, I replaced the valve seals (without removing the head).

Test driving the car it ran well for a couple days then did the same thing going down the hill. This time I just stopped and revved the engine. It returned to normal operation. Since replacing the valve seals, I've driven about 15 miles and lost a little less than 1/4 of a quart of oil but the downhill smoke, rough running problem is still there.

The engine has about 100K miles and injectors were replaced about 6 months ago. It has a manual transmission. In addition to smoke at start up (which the valve seals did not help), there is some smoke with hard acceleration. I've noticed that the car exhaust has a rather arcid smell. Not the typical diesel smell. There is no indication of oil in the coolant or coolant in the oil. The vacuum line from the vacuum pump to the intake has some black in it, but not what I would expect for the amount of oil being burnt.

Any ideas of what is going on or what I should check next?