2003 Idle irratic only sometimes.

I have an early 2003 6.0L Sometimes when parked (so foar only when parked) the idle dropss down to the 640 range and it seems to stumble.

This is what data I have recorded:
Idle normals in PARK:
ICP: 640 psi
IPR: 32%
RPM: 830
RPM Desired: 640

Idle normals in DRIVE:
ICP: 638 psi
IPR: 32%
RPM: 750
RPM Desired: 640

Idle IRRATIC in PARK:
ICP: 640 psi
IPR: 32%
RPM: 580-680 - it bounces around
RPM Desired: 640

When the idle bounces, the ICP and the IPR hold steady.

What I have done to the truck (I drive it very little mileage):
2008 122K
- New ICP and connector

2010 128K
- New low pressure fuel pump

2013 Jan 138K (just about anything I could touch on the top end)
- New heads
- ARP studs
- All gaskets
- New HPOP
- EGR delete
- New oil cooler
- Coolant filter
- New IPR
- Cleaned turbo
- Blue Spring fuel upgrade
- Every improvement upgrade I could find
- Turbo feed line
- Turbo drain
- Stand pipes

2014 July4 145K
- All injectors tested at Superior Dieseil in Detroit
- 3 bad replaced with Alliant Power injectors
- 5 cleaned and new seals
- Changed oil
- Replaced ICP (Crack - Rotella 15W40ed it when doing air pressure test)
- Put in BWD part not OEM

So now it ran great. But sometimes, and not that often, it will get a stumble at idle in park. I have been driving it quite a bit since my other car is in the collision shop. About 1K miles since the injectors done.

I read something about maybe too much oil? It's always been hard for me to se the clean oil on the dipstick, but I think it is to the very top of the dipstick.

My next step, is i've been wanting to do a FICM upgrade.

Any suggestions would help. Thanks.