The Caddy engine was used in the 1980 model year only, as I remember, and had a moveable valve rocker arm pivot that disabled the intake on several cylinders as it cut back to 6, then 4 cylinders in operation. It would drop back to 4 cylinders very nicely, but it was reluctant to come back to full power quickly. Cadillac was replacing engines regardless of mileage a couple of years later at no charge, because the perfromance was so lousy. Maybe Chrysler's got it figured out now, but I'm not holding my breath until it happens!
Jerry
