85 Firebird engine swap? / Troubleshooting

[xtreme_taz]

Hey guys, question for ya! I just bought an 85 Firebird, stock 2.8 ltr FI V-6.
It currently runs very rough, seems like backfiring through the intake, gutless as a hamster too.
Have replaced the fuel pump, control module, plugs, cap & rotor, doesn't seem to help it, any ideas what the main problem could be?
Also, I am considering eventually swapping out the engine and would like to put a 5.0 ltr preferably fuel injected system into it (possibly from an '88 T-bird) anybody have any ideas as to how well that kind of a swap would work.
As you can see, I am not real familiar with the Firebirds or compatibilities with other engines, so any help would be greatly appreciated.
Thanks!

[buzz_42]

If you are going to swap it to a small block, you might as well go with a 350. Right now I have an 82 Trans Am with a 305.. Its fast but not that fast. Im swapping it to a 350... the difference between the 350 and 305 is pretty big... but make sure u have a th350 tranny.... and if u have t-tops get sub-frame connectors

but definately swap to a v8

Lance