i've recently brought a 3.9 efi eb and was wondering if i can convert to carby want to put a four barrel on it or what else could i do to give it more power

If it is for street use, you won't be able to fit a carby due to emissions regs etc.

it all depends on a few things, throwing legality out the window and it is possible to fit a carbi, but there are a few things to consider, is it multipoint efi? is 3 speed auto or 4 speed auto or manual?

1st off fitting a 4bbl {depending on size} to a stock 3.9 is not going to give it more power, if anything it just use epic amounts of fuel and probably make less power than a multipoint efi set up..

if its 4 speed auto you will need to set up a throttle position switch to the carbi so the trans will actually shift gear,

depending on what your trying to do, it would be easier to fit a ed-el or even an au xr6 engine for some extra power..
if you even more adventurous you can convert it to the ba/bf dohc engine..

but always remember power cost money...

change the motor like Troyman said

The word is "bought" lol

but after he bought it he brought it home..lol

pedantic bunch aint ya