Twice in a row I have had a shudder while idling and under acceleration on cold start up. Cleared up after a few minutes. Does not do it after warm up. Today it threw an engine code, misfire on cylinder 4. This is the 3.3 litre. Have just changed the egr valve. Could this be an issue with the coil pack or the brain? There is 274,000 kms on vehicle. Coil pack is $179.00. I don't have the equipment to diagnose a brain fault, so would this be a good place to start before I go to a dealership and get bent over the table? It seems to happen when the temperature is around 10 - 15 C and humid.