well i aint gonna say anything that will make me look silly later
after all i aint worked on nothing but FORDS (for the most part) in 15 yrs,thats why i couldnt remember if it was carb or tbi
i still say check the egr next.if you can pull it off and check it with a vacuum gun,that would be best.you can check it on the vehicle but alot of the times its hard to see if the diaphragm is moving its full range on the car.dont just go by "it holds vacuum it must be good".the diaphragm doesnt have to be bad for the egr to be bad ;)this rattle that you isnt the heat shields,can you tell where the noised is coming from?engine area,under chassis,etc?it is possible the valley pan came loose
but as a side note: you said you bought the vehicle becuase of the reputation of the 3.8l engine
now if memory serves me right the tbi 3.8l is not the same engine as the mpi 3800 engine
not saying tht the 3.8l tbi isnt as trustworthy,but the 3800 mpi is the engine that has the great reputation.
if i remember right the 3.8l tbi was just a revamped 260 c.i. carb engine that they revamped and chopped the back two cyl's off of.
at the time they created that engine they need a 6 cyl that would have some performance and fuel economy to be competitive in the
market at that time, and was the predecessor for the infamous 3800 engine.now the 3800 has hade several versions to date each slightly better than
the last.i believe GM is on the third generation of the 3800 now.
i suppose this is enough of my early morning ramblings. I NEED COFFEE