Check all the intake manifold bolts as they are known to back out and cause temperamental issues (be gentle on the retorque as it's easy to bugger this up with too much cranking down on the bolts).
Check the PCV valve and clean it thoroughly (or replace it altogether)
Clean the throttle body (remove for thorough cleaning)
Run two bottles of Red Line SI-1 Fuel System Treatment in a tank of premium fuel. Run till empty and refill with premium. Do oil & filter change relatively soon afterward as well!
Pull the spark plugs and check them. Clean, regap, or just replace altogether if in doubt
Could there be a possibility of bad fuel gotten into your system?
How do you drive your HEMI regularly?
- Driving Miss Daisy
OR
- Driving Like You Stole It
They have adaptive learning and if you drive it like granny, that's what you'll get in terms of operational prowess, response and performance - "granny mode".
Similarly, the HEMI needs to be driven spiritedly on a very regular basis. They don't like granny mode
Perhaps you have some internal build up that needs to be spanked out of your HEMI?