Ok the car is a y7 and the damm cooling problem is messing up my idle. I've done the cap, plugs, wires, cleaned out the IACV, and still nothing. could it be the Thermostat. It doesn't over heat or anything, just that the upper radiator hose gets really hot. i bleed the coolant and still nothing is doing it, but when i take off my radiator cap, when its cold and wait about 30 min. till it gets hot the idle is fine. Though when i put the cap back on it goes to **** at about 500rpm. Someone help me fix this ****, my muffler shakes like a bitch at 500rpm and tends to be a lil embarassing.

 

is the coolant line bypassed through the throttle body?