heads coming off

I will probably have to order a fancy scan tool soon and see if the built in re-learn procedures can help me.
I followed the re-learn procedures in the factory service manual without using the "HDS" and it seemed to fix my engine light.... except it just came on Sunday morning when my wife started it up. No flashing or blinking light, just a solid light. So I move the vehicle out of the driveway so I can take the motorcycle out for a ride and ignore it. Didn't have my bluetooth scantool to check codes because a coworker was borrowing it. Started up the Pilot this morning to drive it to work and wouldn't you know, no engine light! Weird. Drive to work, everything seems normal like it has been. Get my scantool back and check codes on lunch break. Got all pending codes from random multiple misfires as well as all 6 cylinder misfire codes, so 7 in total. Didn't bother clearing the codes because I didn't want to reset all the readiness monitors nor clear out the idle and crank pattern. Now I'm wondering if the crank pattern was actually learned properly when I did it a couple weeks ago or if somethin else is actually going on that's still causing the misfires. Scan tool reports 10 in.Hg vacuum at idle which seems bad until I get home and run the same live data test on my 2013 Pilot and get the exact same reading! So either that's a normal idle vacuum for Pilots or its the incorrect reading by the scan tool.
I have a mechanical vacuum gauge somewhere in my toolbox but I have no time to dig it out and test until this weekend though I feel it's really unnecessary.
Any other thoughts on sensors that could be acting weird and throwing false data to trigger a misfire?
My last resort will probably be asking one of the local dealerships to let their master tech have a stab at it.

alright short story. wife took the baby out to the store so I got some time to hookup the new scanner to the old Pilot for some good old fashioned data monitoring session.
ran a module scan and fault code scan, found all sorts of fun stuff, mainly the misfires which was expected but also a couple other things, like TPMS sensors not reading and one of the wheel sensors was triggering the ABS and the VTM system so that is good to know because it will probably need replacing soon. Let the engine run for awhile to get it up to temp so I could run the crank pattern relearn procedure which is fully supported by this tool.
It will not proceed with the relearn until the engine temp has met the threshold which is a nice thing.
I probably should have cleared the DTCs prior to doing the crank pattern relearn but I did the opposite.
Cold start misfires were slowly adding up on all cylinders pretty evenly when reading real time data prior to the relearn.
After the relearn while monitoring it caught 2 misfires on one cylinder initially but then nothing else and all other zero so I will call that a glitch and assume all is well for now. Will let the engine cool down and re-test the live misfire data later after the storms move through.
Alright, back to real work, changing the VTM fluid in my other Pilot...

started the engine this morning with the topdon hooked up set to monitor real time misfire data from all cylinders.
outside temp was right around 40 degrees. the ECU was counting a few misfires initially here and there during the first couple seconds of high idle across all cylinders, then as the idle speed started to slow down the misfire counts increased a little bit across all cylinders again BUT never enough to trigger any engine light. actually the counter reset itself several times during the warm up cycle and each time it reset I noticed less and less misfires being counted until finally after I would say around 3 to 5 minutes there were none being counted and everything stayed at zero well before the engine coolant had reached operating temp. it is very interesting that one of the first things the FSM recommends checking after the spark plugs is the fuel system pressure. that will probably be my next step in this process once I acquire a fuel system pressure gauge capable of connecting to Honda fittings. If the misfires were due to a mechanical problem with the engine, IE-valves out of adjustment, compression issues, timing belt, then they would be occurring on a more constant and regular basis.

Pilot was left out in the driveway last night, not in the garage as usual, so a very cold start in the low 30's this morning.
told my wife I would drive it to work and see what happens. Did a key-on x2 the get a little more fuel pressure in the rails prior to starting just in case the pump is in early stages of failing. Started up fine, high idle normal due to the cold, no noticeable stumbling or hesitation, and most importantly NO solid engine light and NO flashing engine light
I wanted to hookup the scanner and monitor misfires again in real time but was in such a rush to get the kids ready.

drove around a good amount today to and from work and out to lunch without issue. I don't drive this vehicle much but it seems the crank pattern relearn procedure helped the engine accelerate and decelerate slightly different than I remember. Maybe it's all an illusion because it was such a nice mild day today. Turning the keys back over to the wife tomorrow. Went thru car wash and it's back in it's place up in the garage. Really my newer Pilot should be kept up in the garage but that's another discussion.
On second thought, the motorcycle should really be in the garage!