So what I am hearing from the mechanic right now for an initial diagnostic that the issue has to do with the turbo and a bad o-ring. They have had a couple turbos in this week that have had the same issue with the same symptoms: running rough when cool, stalling, and running a bit smoother when the engine is warm. I made mention of the vacuum gauge to the person I talked to, but he seemed the think the mechanic was certain that this was the problem. Any thoughts?