Thanks to all who responded to my black smoke problem. Here's what the problem was--perhaps this can help others, too. The egr valve failed--the valve itself had come loose and was able to just flop back and forth. When the turbo spooled up at acceleration, most of the boost went out the open egr valve and out the tailpipe (as I understand it). The engine got plenty of fuel, but not enough air, hence the large amount of black smoke. In order for me to get on with my vacation, the mechanic brazed the egr shut. Now, no more smoke, and way better acceleration!When I get home I'm going to apply what I've learned on this site and remove the egr and its assembly, and buy a 49 state intake.