Just a guess, and I could be wrong, but the first thought I had was worn bearings, Mains, Rod, Wristpin, or all three. How many miles does this car have on it? If it's over 60,000 on a turbo that's been rode hard and put away wet, as we say here in Texas, it might be time to open her up!

If it was mine, I'd park it and ride a bicycle if I had to until I found out what was wrong. This sounds like one of those problems that just gets more expensive by the day.

Just a thought.

-Ralphie