I got my Land Rover Discovery 2 inspected at a Shell station. It didnt pass and came back with multipul codes. Cylinder 8 and 4 misfire, the Idle Control system is malfuncitoning, then code P0300 with random misfiring, and other codes about the ABS. What can I do about the misfing? Ive heard it could be the coils or spark plugs/wires. I installed new spark plugs and wires about 3 weeks ago. Some one help! Thanks