There are several old threads that appear related but were disjointed, and lacking resolution
'06 H3, 5cyl, 152k miles
Original problem started with an oil pressure light. Initially presented itself at low rpms (500-700 at a stoplight, etc.), and only after engine was warned up - so seemed like a pretty legit presentation for a bad pump, etc.
My mechanic ran a ton of diagnostics, and said no sign of low pressure, but the error codes led him to the MAF, which he replaced. The engine continued to throw various lean codes (P0420). After running through compete diagnostics, he said we needed to replace the PCM. I was reluctant, but I've known him for years, and always done great work and he was positive this was the issue.
Picked up the truck after the replacement PCM was programmed, and barely made it 20mi before oil pressure light came back on.
More diagnostics - but everything was clean (no signs of sludge, once again checked for debris in pick up tube, etc.,). I bit the bullet and agreed to replace the oil pump which was a bit worn, but not terrible given the mileage.
Picked up the truck again, and made it to the same exit before oil pressure light came back on.
He went through everything again, and then drove the truck himself for a week - nothing.
Picked up the truck again, and drove it for 3 days. While the truck was idling, CEL came on w/ Stabilitrack and then "Reduced Power Traction Failed" and the truck just died. I've read several similar threads with this symptom - truck would not re-start for several minutes. Was finally able to re-start, but same sequence occurred as I headed to the repair shop - CEL light, Stabilitrack and then "Reduced Power Traction Failed" and everything went blank (always fun losing power steering on the highway). It was throwing a P0601 error code.
Back at the shop, we're were able to replicate it several times while checking all the connections at PCM, throttle body, battery (2 month old battery, and I long ago replaced the terminals).
Perplexed, mechanic threw the original PCM back on. This cleared the P0601, CEL, Stabilitrack - but after driving for a bit it threw a P0420 lean code, and then oil pressure light again.
I've seen several people suggest the throttle body as a culprit, but it would seem swapping out the PCM would help rule this out.
.... anyone have this figured out?

 

You have separate issues happening.

You did not need a replacement PCM. Lean codes usually are from an intake leak downstream from the MAF, you likely did not have to replace that, they should have cleaned it first.
When was the last time you changed the air filter?
When was the last time you cleaned the Throttle Body?

Check the air intake and filter are properly in position, make sure all the Intake Manifold fasteners are in place and properly tightened to 10 N.m/89 lb in.

I would change the Oil Pressure Sensor (OPS) before I would ever replace an oil pump. Anybody check the wiring and connectors to the OPS?
While looking at connections and connectors, how about all the ABS wheel sensors? Easy stuff first.

 

Thanks for the reply.
Air filter was changed less than 6 months ago, and throttle body was cleaned in early October (~2.5 months).

They did check the OPS prior to changing out the oil pump - all looked fine.

Have not checked the manifold fasteners or ABS wheel sensors.