Little lady mechanic

I did just find that there appears to be a bolt in the very back of the bank one manifold there a hole there for one. It appears to have broken off at some point. Could that be the problem? And how would you even begin to remove the stud left over if there is a broken one in there. It’s the last hole by the firewall

The code that always pops up is P219A bank 1 air/fuel imbalance then occasionally P219B bank 2 air/fuel imbalance. Then every once in a while I will get a P303. Other then the codes popping up the truck sounds and drives fine. Although on hills it likes to stay in a lower gear so it sounds more ruff and I can occasionally feel that cylinder misfire I think. I have a fixed reader so I’ll attach the last freeze frame from today cause that 303 code popped up again.

I have had my truck for about a year now and ever since I bought it its been throwing this code I need help narrowing down the causes. usually the check engine will light up usually after about 5 miles of driving it or on a hill then after I clear it It may come on again in 50-100 miles seems to do it more at a full tank and then after half a tank gone. p219a shows on the scanner every time occasionally it will throw P219b and a and then once every couple of months it will show the first two codes with a misfire in cylinder 3. now I have done the spark plugs and swapped coils for cylinder 3 and it still shows c3 misfire. I have some screenshots of the data shown when the code happens if that will help anyone figure it out for me. the emissions results when it scanned always have a failed evaporations system, either oxygen sensor heater fail or oxygen sensor fail sometimes both, check engine light fail, and trouble codes failed.