I am trying to find out what all (if possible) do I need to do in order to switch my 3.3 to 3.8 in my 01 caravan? Heads are gone on 3.3 and just not enough power for me. Can anyone help me out?

 

Engine is all you should need as the stock ecu/harness interchanges.
If your 3.3s heads are gone, rebuild them and do some port work, it will easily put the power over the 3.8L.

Realize the 3.8l makes 15hp more then the 3.3l. The 3.3l can easily be mildly modded to produce more then the 3.8l, and won't require the work/expense of swapping an engine.

 

Also check compression on whatever you're going to put in even before you buy it. You'll be surprised how often it's bad with most sellers.. If you have a clean and well maintained 3rd or 4th gen it's almost worth it to just go get a crate engine because used sellers are almost always low-lives who really know nothing about the engine they're selling.

I currently have a '03 GC Sport fully loaded with a 3.8 swapped in over a 3.3. You can actually do the swap in days if you can free the time for whole days.