[kingnutin]

Well, you could certainly use a flush from what I see in those pics. The problem could be a head gasket, the indicator being the gas smell in the reservoir. The only thing that would cause that, is combustion gasses getting into the cooling system. Oil and coolant mixing does not necessarily occur, and even when it does, it can be an intake gasket problem. Another possibility is that the coolant was low to start with, if its low, you will get air pockets in the engine which will cause it to overheat. Which would leave the question of where the coolant went, has it been leaking? Last but not least, do the fans run when you idle it? If not, that is probably your issue. Head gasket could also have failed as a result of overheating from another issue.

 

[kingnutin]

A bad head gasket will give you constant bubbling in the cooling system, which may or may not come with exhaust or fuel smell. May or may not cause cross contamination of oil and coolant. May or may not allow coolant into the cylinders, which may or may not come out the exhaust and may or may not plug the cat. Point being there are a lot of variables... Radiator failure is usually limited to leaks, but they can get clogged and block flow, but you would have hoses swelling from excess pressure. Thermostats typically fail open, but can fail closed, similar symptoms to clogged radiator. Water pump will either leak, or the veins can wear out and it will stop flowing properly.

If I were you, and you have tools and space, I would just go ahead and tear into it down to the head gaskets. Replace the thermostat, temp sensor, and water pump while you're in there, which is going to cost an extra $50 at most. Do a flush before you start to clear the heater core and radiator, you should cover all your bases. I really think its a head gasket.

 

[kingnutin]

Why on earth did you get an oil flush?

 

[kingnutin]

Gas smell in coolant reservoir? That would point to a bad head gasket, which could also explain the misfire.