I grooved the family car last week (yes we have a big family), its a 15 passenger van.
First off it was a pain in the butt to get the TB off. Far enough back that you can just barely reach it and its about the same distance if you take apart the dash and get at it from the inside.
I did not cap the pcv or and of the vacuum lines. Mainly because they were all just so dang hard to get too!
Originally it got between 10 and 12 mpg average.
We took it on a 200mile round trip the other day. On the way there we averaged 17mpg (i was using my kiwi OBD2 scanner) and we had a really strong head wind.
On the way home the wind had died down and we averaged 20mpg the whole way back.
That's over a 60% improvement if you compare the averages! That's incredible!