I have a feeling if you did everything in the list you'd still have practically the same output of the 3.8 or less. I'd probably look in to options for the 3.8. Primarily heads and cams from something that uses the same core. I don't think there are PCM options to make most typical upgrades matter.

I came across some guys locally who did a 3.3 to 3.8 swap in a 2004.

EDIT: What effect would a dedicated oil cooler have?

 

Intake and exhaust is about as far as the stock ECM can handle on the 3.3/3.8, so without going stand-alone, options are limited.

I don't understand a 3.3 to 3.8 swap? Swapping an engine for 10hp seems like a waste of time.

An oil cooler would help oil temps, most likely oil/engine life, although I've never had an oil issue on the 3.0.

Another great feature of the 3.0 is it can handle boost with the stock ecm/fuel. This gives the opportunity to make 250+hp with no other mods, which neither the 3.3 or 3.8 can do in stock trim.

The A670 trans can also be modded to handle extra power pretty easily.

 

3.8 is 25HP over 3.3 and 65HP over 3.0 on 4th gen without any mods, about the same for 3rd gen. For PCM I don'y even think there are PCM mods for 2nd a 3rd gen of any power-train option.

I look at it from a durability and fuel cost perspective. All these mods don't deliver enough power to make it worth it, even ignoring the weight and body type it's for.

 

Ney-say as you will. These mods are tried and proven for 3.0's. If you don't want to mod your van, dont. I'm sharing knowledge to those that may, but think there are no options.

Megasquirt can be adapted for Stand-alone management. So the option is there.

I had 200k of abuse on the 3.0 I pulled out. Only reason it came out was to put a built one in, so durability on the 3.0 is not an issue, factory crap tuning is.

As far as fuel cost, the 3.0 runs excessively rich from factory, a lot more air can be added without extra fuel coming in to play, which makes them more efficient.

 

People willing to try and wanting more will see the gains.
3.0s are a very under-tuned motor from factory. There are many gains to be had just cleaning up factory slop (aka-Casting lines in the heads).

They were originally rated at 141hp @ the flywheel. Mildly modded 3.0s have put down over 160whp (roughly 190hp @ the flywheel). That puts a mildly modded 3.0 equal to a 3.8 only with a better usable powerband (2200-5500).

Instead of falling on it's face around 4k a modded 3.0 keeps its power all the way to the rev limit, that in itself makes them much better performers.

 

To iterate on the under-tuned. A stock 3.0 is only running about 62% VE (volumetric efficiency). That's pitiful, that's also why they do so well with tuning.
That also says there is a ton of room for improvements.