lex1220

I have searched and didn't find anything similar to what I have going on. On my 92 SC400 this past week if I let it sit for a few minutes after warming up (3-5 minutes) the car starts to over heat but if I pop the hood or start moving the temperature drops. I was at first blaming the hydro fan solenoid that tells it when to accelerate the fan but now I am wondering if my idle is to blame. If I am correct if my idle is too low, the pressure required to push the fluid and spin the hydro fan will not be adequate enough to move the fan at the speed it needs. I have noticed over the past week or so my car SOMETIMES idles at around 250-300 RPM. Today I sat in the car with it idling at around 450-600 RPM and it did not start to over heat and the fan spun at reasonable speeds. I have not payed attention yet to the idle speed when the car starts to over heat which I believe is the next step I should take. So my question is this; is my theory about idle speed/fluid pressure correct? and if so what should I look at to fix my idle speed from dropping down so low? I know the end all issue is to use the LS400 bracket and go to E-fans but if my idle is to blame I would rather invest time and money into correcting that. Thanks all!