it's dripping fuel while not running right..?
if so, then you need to replace the injector/s o rings...just buy a TB rebuild kit, it will have all the gaskets/seals/ and o'rings needed for a complete rebuild...it would also be a good idea to replace the fpr while it's apart....
you need to warranty the engine asap....Grooms will stand behind it if it is indeed their fault....
http://www.turbobuicks.com/forums/buick-v6-turbo-tech/48429-grooms-engines.html
First, check for any stored codes....
http://www.extreme-check-engine-light-codes.com/GM%20OBD1%20Decoder.htm
if no codes, then check fuel pressure, it may be a slowly dying fuel pump, or a bad fuel pressure regulator....
like most others in here, i have a 5-10 second knock at cold start up(only in the winter months)...then she's good to go...
and +1 to if it's knocking for 3 minutes, then you have a motor fixing to go down on you...better be finding a replacement or rebuild soon...