jayroca tried the flex plate game too and ended up buying a 2nd gtp i realize its not the same vehicle but id be damn suprised if its anything besides the bottome end.
Tell you the same thing i did him instead of start it and rev it 30 times to try figure out what it is do the easy things pull the plugs check them drop the oil and see if its glittery, then pull the cover by the flex and see if its cracked or broke the bolts off.
Sorry man my moneys on engine went bye bye.