The original symptoms were massive engine overheating followed by non-responsive or very jerky accelerator response. Trip to the mechanic said it was likely a leaky head gasket or cracked head, but that the quoted repair would be greater than the value of the car. Said if we had the time and gumption it was something we could do ourselves. So after dissembling to that point, we took the head gasket back up to the mech who said it didn't look like any cross cylinder leaking was happening through it, and had the head pressurized that determined the head was not compromised. All four pistons have some carborization on the piston faces, the number 3 cylinder has a touch of rust on the piston face, and upon dropping the oil pan there appears to be water/coolant in the oil (segregated bluish liquid in the oil pan).
My question is: Does anyone have any ideas on what's wrong? Where do I go from here? It's a fair bit greater job to drop the pistons out to look at the cylinders more/change the piston rings, but if I've come this far and that holds the possibility of fixing the problem I'll try it. Or do I just clean what I can from where I am, replace gasket, put it back together, and pray?