I stated concentrated, ie; non-diluted, because when you flush the system as described, you will be left with water still in your system.  By using the concentrate, you will be close to a 50 / 50 mix.   BTW, the concentrate is cheaper than the 50/50 mix from the supply store and you are paying for water. As 1004ron said, I also buy the concentrate and dilute on my own

Not sure who that comment was directed at?   I always buy the concentrate and mix it 50/50 and the product details state clearly not to go higher than 60/40.   My comment was to drain/fill a few times with distilled water and that way you would have removed about all of the old coolant mix, then go back with say a 60/40 mix knowing that the engine still contains some straight distilled water.   I use a vacuum fill kit similar to this. 

Not sure why you recommend pure antifreeze?  Pure ethylene glycol freezes at 10f.  The normal 50:50 mixture freezes at -35f.

One could also use a system like the following to flush out the entire system and then fill with concentrated ( non-diluted ie; 50/50 ) anti-freeze   https://www.amazon.com/dp/B0002SRH5G/?coliid=IBXVQ52CJGVOB&colid=1VY88PYQ3KPE1&psc=1&ref_=list_c_wl_lv_ov_lig_dp_it  

Ya but up here it’s a Ford Titanium Eh! lol  

"Must have been RockAuto." - That doesn't sound like a confident response to me.   Reliable code reading is the best starting point.   .

The only way to get only the new coolant in the system is to do a few drain-fills with distilled water and then the final fill with a higher concentration of the new coolant expecting some distilled water to remain in the engine.    

Just remember you are not completely draining the coolant from the engine with a normal flush.  Old coolant will still reside in the engine so this may be the cause of your " green "coolant.

Just remember I said that something wrong with the PCM is a possibility, not the actual cause.  Agent 1004 seems confused.   As previously mentioned / questioned, are the spark plugs / coils of known origin?  You mentioned Rock Auto.   Have you checked all spark plug / coil connections to be certain they are secure?   Where do you buy your fuel? I have had past issues with fuel sources that have created intermittent issues like you are mentioning.  Even trusted fuel stations in the past were no longer trusted.  Stations are susceptible to leaky tanks as well as buying cheap fuel from other sources, ie; not Mobil fuel from a certified Mobil distributor so they can increase profit on fuel sales.  

Sounds like something loose in the suspension.  Could have a loose / failed rear shock, which would make it simple to fix.   Have you looked around the area to see if you can see anything out of place; ie: loose inner fender well, shock not properly bolted in place, etc. You can only see so much with the wheel / tire installed.