Results: $0.71 pot ($0.03 rake)
Final Board: 8 K 6
Hero mucked A A 9 3 and lost (-$0.22 net)
SB mucked and lost (-$0.22 net)
MP mucked and won $0.68 ($0.46 net)
yea gotta fold. big problem (aside from your hand) is that u have 2 players still behind u who could have u crushed as well
hard to tell exactly what his range is since this isn't the most common line (limp/call then donk pot on the flop) and you didn't provide any reads (even just vpip/pfr/3bet helps a lot here)
He has just 1 player left to act behind him, but regardless - I agree that a fold is in order.
I gave MP a 50% limping range excluding a 12% opening range. I gave SB a 25% flatting range excluding a tight 4% squeezing range.
On the flop I gave MP a quite liberal potting range of K6+, 2nd nut FD or better, 975/T97 and any pair+fd. This is a 30% donkbetting range which is very optimistic. You have 42% equity heads-up against MP, but your 3-way equity is only 27%. If SB decides to shove you are in a very bad spot and have to fold. Since you're not making that much on the call to begin with, you cannot afford getting blown off the pot 15-20% of the time when SB wakes up with a hand.
Tightening Villain range even slightly to a 20% donkbetting range { K8+,(K,8,6) : (579+,Qhh+),Khh+ } and you have 40% equity HU and only 25% 3-way. SB actually has more equity in the pot than you right now (26%), and he has any 4 cards from a 25% range.
Can't see why this would make much of a difference in this particular spot. Any pot-sized raise will basically be a shove, so it doesn't really matter. I guess villain can more easily deny us equity by just going all-in on the turn, but I don't think we can call a pot sized bet on many turns anyway.