when u start it cold and let it idle, open the coolant res. and check to see if there are any bubbles, if there are bubbles you need to take that head of yours off and send it out and check if the block is warped also
did they bleed the system properly? maybe ur head gasket is just gone.
i had a s13 with sr and it used to heat up all the time because the fan wasnt good enough.
ok do this… make sure the engine is BONE cold…
put a pear of thick gloves on and wear a sweater… maybe even saftey glasses
open the rad make sure its full of fluid.
start the car (with rad open) and repeatidly squeeze the big hose coming off the rad(left hand of motor) entering the motor
repeat untill the thermostat kicks in (it will start pumping out HOT fluid)
with gloves on and ready put the cap back on… you should be good after this procedure… it helps to get out air locks in the system… like priming a fuel line, the air literally gets trapped in the water… dont know the science just that it does…
what type of fan do you have? i had the same problem before cause my fan was not working properly. now i have the stock clutch fan, no overheating problem what so ever.