l86 dod delete: stalling and inconsistent idle after startup

[persistent]

i've completed the mechanical work for a dod delete on my 2020 l86, and i'm having issues with inconsistent idle and stalling after starting the car up. i have used hp tuners to download ecm, flip dod setting to disabled, and written the modified image back to ecm.

here is a summary of what i've swapped out during the dod delete work:

- replaced stock camshaft with TSP-316804 "oem-style non-dod" camshaft
- replaced stock lifters and pushrods with BTR LS7 lifters and 7.800" pushrods
- installed oil port plugs under vlom cover
- replaced vacuum pump with oem part
- replaced water pump with oem
- replaced phaser sprocket and timing chain with oem
- replaced oil pump with oem
- replaced valve seals, springs, caps, and rockers with oem

here is a summary of what i've done in terms of the work:

- checked the timing marks lined up between phaser sprocket and camshaft sprocket several times before closing the timing cover
- followed service manual instructions to apply upward pressure to new oil pump while tightening fasteners
- walnut blasted and manually cleaned intake ports on heads
- removed nearly all carbon buildup on intake valves
- primed the oil system by using a starter relay bypass tool prior to starting engine
- all fluids have been changed, including transmission fluid, but i have not yet flushed and brought transmission fluid level up from what i pumped into the pan (4 qts)

i have let the car idle for a total of roughly 5 minutes so far, and i decided to shut it off in case something was wrong with it. i saw the tachometer start fine, the rpms drop below 1k, and it would dip towards zero episodically. in some cases it stalled straightaway on start.

i'm unsure what steps i should take to diagnose and fix the idle problem. maybe i just need to let it idle for a while to warm up or tune it further, but i have no experience doing this.

EDIT: something else i thought could be relevant is that this car has sat for 3 months while i worked on it. perhaps stale gas could be an issue.

 

[persistent]

i've started the car again and it does idle without trouble, but i'm seeing and hearing a yoyoing between 450 and 750 rpm. in vcm scanner, the timing advance goes from 0 deg to 30 deg before dropping back to 0 deg and repeating with the engine speed yoyo.

 

[persistent]

talked to a friend of mine that has a lot of track cars, and he suggested i check the camshaft position sensor and cabling after i mentioned the unstable timing advance.

sure enough, i checked the 3 connectors on the timing cover and 2 of the 3 were not locked into position with the tabs down. reseated 1 of the connectors, pushed in 2 retaining clips, and now it's got a steady idle. the timing advance value has stabilized substantially from the prior behavior of it sawtoothing.