Every 25 seconds idle drops to almost stalling for a few seconds then comes back up. Idle has continually become choppier.
05 6mt sedan so revup. Has standard breathing mods, uprev tune. Setup has been the same for years without issue.
118000 miles so I replaced pcv valve, new ngk spark plugs, hitachi cam, crank and maf sensor. NTK O2 sensors 4 years ago.
I've reinstalled and re-torqued the MREV2 plenum and 75mm tb adapter. Capped off vacuum lines and sprayed brake cleaner looking for leaks.
No codes.

 

1st thing I'd want to rule out for a fluctuating idle is a vacuum leak after the MAF. Buy/borrow a cheap guage and connect it to your intake manifold. If you have the stock air handler check the hose underneath for any tears and double check clamps to be snug. Do not clean the throttle body without disconnecting it. Gl!