Does Decrease In Lisinopril Intake Cause Fluctuating High Blood Pressure?

I had CABG 8 weeks ago, and have been on a steady regimen of Plavix, Amiodorone (250mg) once a day, Lisinopril (10mg) once a day and Metoprolol (25mg) twice a day. At first, my blood pressure was steady and excellent, averaging 115/60. However, my cardiologist stopped the Plavix after six weeks, and reduced the Lisinopril to 5mg. Shortly afterwards I started having wild swings over each 24 hour period, with resting blood pressure high to very high (150/80 to 170/105) early in the morning when I first get up. As soon as I become active, it steadily decreases, and reaches an average of 120/60 or lower by 3PM. After exercising and cool down, it will drop to 105/50 and stablize in that range for several hours. As soon as I relax, e.g. watch TV, in the evening, it begins to climb again. Should I ask my cardiologist to go back to the Lisinopril 10Mg or is something else indicated?