This:

https://www.carscanner.info/

 

P0171 is an odd code for our vans.

• Is the rear valve cover gasket dry out and brittle causing oil weepage and air leakage. The engine will idle rough.
• The PCV and/or the rubber ring it sits in is torn, old or cracked.
• Both of the above can leak oil residue onto the O2 sensor just behind the valve cover causing this code.

P0171 refers to an imbalance in the amount of air and fuel entering the engine as the vehicle operates.

• old emission hoses that are dry or cracked.
• Failing fuel pump or a weak fuel pump.

P0171 also is a hint

• The CAT is having problems due to the engine running too lean.
• MAP sensor for fuel to air mixture is not monitoring correctly and has gone bad.
• The fuel pump regulator has gone bad.

 

also wonder if this could be a bad O2 sensor, or if there is something stupid simple that would cause this

Welcome aboard,
not what you want to hear, but this:

Melted injector wiring harness 2003 Town and Country

Finally! I found it! I had codes p0300, p0302, p0304, p0172 and many others. I changed so many parts. the wiring harness was melted together, just under and behind the power steering reservoir. I taped it all up with a mile of electrical tape and gave it a lot of heat protection wrapping...

www.chryslerminivan.net

 

In regards to the dried out valve cover gasket, the head gasket was changed earlier this year, so would think those valve cover gaskets would be shiny and new. I will look into the things you mentioned.

This engine is throttle body, so would it be subject to the melted wiring harness?

 

@atoman has a good point toooo. Check the fuel injector wire-harness. Your year was PRONE to this problem AND the hard running is exactly what you are experiencing.

 

Ok... Update... I was completely wrong about the engine. I referred to the under hood sticker until I actually started trying to decipher things. It is actually a 3.3. That said, valve covers are not leaking, cleaned MAF, and MAP. Wiring looks intact and doesn't appear melted. Don't see any hoses cracked. Am gonna change PCV valve, and I think fuel filter...... Trying to find a way to get live data, but until then looking into fuel regulator, and gonna try to do a fuel pressure test.

 

...That said, valve covers are not leaking, cleaned MAF, and MAP...

Just so you know, your van doesn't have a MAF, most likely you cleaned the Intake Air Temperature (IAT) sensor, that's the sensor in the intake tube between the air filter housing and throttle body.

 

no MAF as you engine is sefi system peed density not mass air flow so no mass air flow sensor so you did not clean one

the is a MAP - manifold absolute pressure sensor that measures pressure not air flow