'02 caravan 3.3ltr 70k, fuel injector #1, to much fuel into cylinder. o-rings or a bigger problem? had scanned just before being told this, and code P0172 fuel system rich came out. but one day earlier scan said bank 1 system lean so i changed downstream O2 sensor. no acceleration rough running. any ideas?

SOURCE: OBD II DTC P0172

p0172 is not a volvo code so may not be correct but converted to volvo is code 250a long term fuel upper limit (lean vac leak) ck all vac hoses and replace the canister purge valve mounted on the radiator (about $40.00 part) then reset all codes

SOURCE: 1999 dodge dakota p1762 code

dont know lots about this witout engine size but some have 1 coil per cylender possible coil is bad or plug 02 sensor will cause some problems but a miss fire will cause it to run like trash

SOURCE: location of O2 sensor in bank 2, 99 5.4 expedition, running lean

I have a ford 2003 windstar that was running very rough when cold and almost stalling. engine light came on. went to autozone and they read the codes for free and told me it was running lean on Bank 2 also. i came home searched for the O2 front sensors online using the info autozone gave me. there are 2 front sensors on my car that need to be replaced at the same time. look for ones that have a direct plug in and don't need wire splicing. the ones without the wiring harness are cheaper but more of a pain, i think.
they were fairly easy to replace. getting access with the wrench was the worst. reset the light by disconnecting the battery for a few minutes. seems fine now and the light hasn't come back on.

SOURCE: PO171 error code System too lean bank 1

Here are some possible causes, I would start with anything related to replacing the intake.

Air leaks in intake manifold, exhaust pipes or exhaust manifold
Fuel control sensor is out of calibration
Low fuel pressure (fuel filter clogged, pressure regulator failure)
One or more injectors restricted or pressure regulator has failed
O2 sensors contaminated, deteriorated or has failed
Vacuum hose is disconnected, broken, leaking or loose

SOURCE: Check engine light. got 2 codes P0172 and p0175.

Unclip the 02 harness, then take out the 02 sensor. 5 minute job.