Ok guys, i know i am on here alot with questions but i need help with a new one. So I have been trying to fix this throttle hesitation bull crap that my stang is doing so i figured running fuel injector cleaner in it may help. so i used it and filled up the pony. Started driving it around, then stopped to talk to a few guys and let it sit and idle for about 10 to 15 minutes until i decided to leave. So i left and got on it a little and it felled like dog crap, didnt even grab second Then I looked at my temp gauge and it was reading 220 degrees. knowing that is to hot i immediately pulled over and shut it off. I got out and released pressure from the system from my radiator cap. Then i saw it all bubbling in the puke tank when i pooped the cap off of it and antifreeze started leaking on the ground. I honestly have no clue where it was coming from but it looks like either somewhere on the backside of the puke tank or on the bottom of the radiator. Well it stopped after the pressure the pressure was all out. so i started it back up and the temp guage started to drop to the normal 200 degrees. so i drove it home gently and it stayed right at 200 and really did not go above that. pulled in to the house and NO leaks. I just changed the thermostat about a month and a half ago but never know could be sticking not sure. I am boggled about it so sorry this is so long but just wanted to give the full scenerio. so if anyone knows please give me feedback. thanks  

what kind of radiator is in the car.what kind of fan,and ifit is mechanical,are you running a fan shroud.also,what temp thermostat is in the car.the other thing is how old is the radiator cap.if it is not holding pressure,it will overheat  

I have a clutch fan which i have think the clutch is going bad anyway. But I drove the car about 60 miles today just to see if it would do it again and also to get that injector cleaner worked around. Drove it around and it stayed right where it should at about 200 degrees and drove perfectly fine too. i have a new 195 degree thermostat in my car now i was thinking about dropping down to a 180 i have one in the garage but i was told that it would mess with my computer by putting it in. its probably acting up because i said i was going to sell it for a hatch. I dont know seems like a freak thing to me since it is not happening anymore. what do you think?  

it sounds to me like you have a combination of things wrong.it only overheats when it's allowed to sit and idle for any length of time.i would change the fan clutch,and the radiator cap.also run some water wetter.leave the thermostat alone,as the lower temp will mess with your fuel curve.but it really sounds like the fan clutch is your main problem.  

I agree with everyone else in that it could be a number of things.   However, since you said you recently changed the thermostat, I would start there.  Assuming the car didn't overheat before you changed it.  1) make sure the thermostat is installed facing the right direction.  I know it sounds silly, but it happens all the time.  2) Make sure its a good quality, high-flow thermostat.  3) When you changed the thermostat, its possible there was still too much air in the cooling system.  You need to pump in coolant, either with a pump or with the engine running.  Air bubbles can cause it to overheat.    Have you heard of Motorator.com?  There is a great question and answer section with a lot of really smart Mustang guys.  You can probably find more help there:  http://www.motorator.com