If you suspect a head or head gasket problem, test for exhaust gasses in the coolant.

If your head is good, check the basics. Search for threads on overheating, but please don't drag up ancient threads! Use the info in them, link to them in your new post if needed.

 

I recommend starting a new thread with your symptoms, and include important details like what year/engine/trans.

 

One of the easiest ways to tell if your boiling coolant in the engine or head is to remove the front pcv hose from the fitting in the valve cover and the intake pipe...plug the fitting on the intake pipe. ....install 3 feet of clear 3/8 tubing onto the pcv fitting on the valve cover and just let it droop over by the brake booster...drive around for a week or two....if that clear hose fills up with white or yellow snot you are boiling coolant thats in the oil....if it turns amber or brown but not snotty...you will know the difference instantly...then your head and gasket and block is intact with respect to the coolant

 

Ive seen cases where the transmission heats up when accelerating or under load or particularly up hill which causes the car to over heat during acceleration as the transmission oil is cooled by the radiator.
Checking transmission fluid in this situation might be a good idea just incase the trans is boiling up.

 

That is a possibility if the trans is slipping badly. Either due to low fluid, improperly adjusted throttlebody cable, or the torque converter not locking up.