03 Caravan intermittent miss, IAC @ 255

[mike5plus5]

2003 Caravan 3.8 has me puzzled. Sorry for the long explanation below but it's needed since I've done a lot without a solution yet.
Ongoing problem with intermittent miss/misfire, engine cold or at operating temp.
Sometimes runs fine/ sometimes frequent misses. No misfires are ever recorded by PCM real time nor in misfire history
(via Matco Maximus 3.0 scan tool)
Recently got P0171 (lean condition) due to bad fuel pump (I heard the old whining pump's pitch go lower right before setting code). Replaced old pump (44 psi) and inline filter - new pump is 55psi, within spec (58 +/-5).
No DTC's ever since pump replacement 2 weeks ago but miss issue persist.
LT Fuel trim 12-14 at idle, lowers at off-idle RPM sometimes quickly, usually gradually.
Short term fuel trim is responsive and follows 02 sensor signal well.
Primary O2 sensor switching above/below 450mv well.
*According to scan tool data stream, IAC valve remains at 255 steps (replaced IAC valve/motor with same result)?
Idle speed is within spec ~750 RPM.
TPS sensor voltage follows actual position smoothly.
MAP, IAT, Coolant temp are accurate in-spec.
Cleaned injectors today, ran good at first then intermittent miss returned.(may be coincidental?)
New spark plugs today (.050 gaps checked) = no change.
No vacuum leaks can be found via carb cleaner sprayed around possible leak sites (intake manifold, injector o-rings, vacuum lines, etc.
No vacuum leak found via clamping off vacuum supply lines from intake manifold to accessories (brake booster, EGR, EVAP, etc.)
No vacuum leak found using smoke machine other than smoke coming out of intake duct at air cleaner.
Any suggestions very welcome!