sounds like a CCV failure. Your oil consumption up? A lot? The blast of smoke is intermittent and no correlation to anything else? That's a CCV problem. Won't show up in a scan. Most likely problem is the flow back tube from the CCV to the dipstick tube. The collected oil in the CCV is supposed to flow back to the dipstick tube and back to the crank case. When the flow back tube collapses, the oil builds up in the CCV and then gets sucked into the intake resulting in the unpredictable clouds of smoke. Replace your CCV system with a cold weather version and I predict your problem will be gone.