My gp threw 2 codes. The first was my cam sensor and the the second was my egr valve. I replaced both of those, but now my car is reading that my egr valve is malfunctioning. And when I start it and let it sit for 15-30 seconds, it will start increasing rpms then drop. Sometimes in reverse it will bog out and die. And also for the first 5 minutes of driving it will glitch out and the car shakes for a second then stops. What is the deal?