88 Legend stalls when I put the clutch in.

When the car is cold it starts and runs. The Check Engine Light has been ON for over a year. When the car gets warm and I have to stop, I put the clutch in and the car stalls alot. I found a code 7 reading on the ECU. The car used to go through 2 quarts of anti-freeze a week. Now after 2 months it has used less than a quart.

Thanks