can i replace a 3.3L with a 3.8L?

If the engine mounts line up then theoretically yes. Idk off the top of my head if they do. But your asking for a lot of work. I mean A LOT of work. Thats more like a project not a weekend thing. Also it would need a lot of tools maybe a new transmission, new harness, A lot of money. A lot of parts, A lot of head scratching, and high blood pressure. The easiest way to do it is to find a donor car. Yet to be honest thats still a lot of work. If you want more powe, simply clean the engine, new fuel injectors, o-rings, spark plugs, etc. Then add a turbo or a supercharger. And just get a small stage one. That would be a lot easier. Consider though any mods usually shorten the life a car significantly. But if you do end up changing good luck. Hope this helped.