having trouble

wel i have a 1990 miata, and i have been trying to figure what is going on.
My car begins to overheat on idle and when im at the highway. If i drive for a while then i come to a stop on a light, after a few seconds my temp gauge begins to climb. Also when im on the highway as soon as i begin to climb 60 and up same thing the temperature begins to climb. This has never happen before until the summer came this yr. I have owned the since october of last year so i dont know if these symptoms exist before.
When i finish driving i head home, i always park the car in the garage. Except of ramdomly turning it off i let it sit for a while for i can see if theirs a leak, or something not working. As soon the temp gauge goes past 12 o'clock the both fans kick in, then goes back down again. I have waited about ten minutes and nothing the gauge will stay normal.
So far what i have done was i replaced 4 hoses, the top, btm from the radiator, as well the hose that connects after the btm hose that rises up towards the hood then bends back toward the engine. I have also replaced the small hose that comes from the thermostat housing to behind the power steering belt. I have just recently replaced the water pump back in april of this year, due to doing the timing belt job. I have already replaced the thermostat 3 times, one back in april when doing the water pump change, 2nd on the 11th of june due to i sent out to get my radiator rebuilt, and last one was last night and the car still overheats.
Then i drain more coolant to add more water and water wetter then i go ahead and burp the radiator. At that time i also replaced the radiator cap with a new 13lb cap. When trying to burp the coolant i notice that my thermostat does turn on cuz i notice the coolant running when it gets low i added more. I sent to get the radiator rebuilt what they did is they sealed off the cracks it had and they recleaned the fins and ran wires to clean the ports inside the radiator, i was told that the radiator looked fairly new didnt have any build up inside.
Is their something im missing?
my car still over heats at idle either when its hot and sunny outside or night time now.

Hey! buddy is good to see u been eliminating choices and narrowing down the problems my recommendationwill come after a question. Do you still have the factory radiator aluminum with the plastic tanks? a repair is not enough in most cases most of the times when a radiator closes in the 100K miles is good for replace most miata radiators I seem to have fail between 100 and 150K if I were you I would replace it completely for a new one that will be peace of mind my friend, Otherwise wait until the car is said to be overheated and pay attention to the operating temperature maybe is just the gauge acting up. If you got any other concern u can contact me at [email protected]