hello again, sorry for the long posts, (get a cup of joe for this one)

first of all, you would probably have your problem diagnosed by now if you had your mechanic (or mechanical friend) look at your car again. it is so much easier than using a forum...

by the way, IF... the only coolant you lost came out just from opening the radiator cap...you probably didnt lose that much water...when the pressurized cooling system equals out with the surrounding air the water quits gushing.(this SHOULD have only been a few seconds in duration) i have yet to see a car gush itself dry, because once the coolant level gets to about 3/4 full there is no physical way that the coolant can expand enough to even reach the radiator cap. (Just the fact that liquid came out shows that you had a decent amount of coolant, otherwise it would only have been steam.) so as long as your engine now runs normaly some of the time you can be pretty sure that you didnt damage your head or other major mechanical part. but if it now runs like crap all the time , you may have a mechanical problem.

your car only idling at 200 rpms is not uncommon for an older vehicle when it is super-hot(such as fifteen minutes after you turn it off, when all the cooling devices like fans and waterpumps arent turning.) its probably just a sign that it is out of tune and has old and worn out sensors (which could be your problem to begin with)that cant adjust the super-hot air/fuel mixture enough to run well at those temps.. (every older vehicle i have owned runs poorly at those temperatures) but it should improve as you drive. by the time the engine returns to normal operating temp. you should see all your power and idle speeds return to normal....

because you say this happens at norma temp. also... the only way the engine problem could be cooling related is if your temperature gague is not working properly and showing normal temp while your motor is overheating to the point where it cant run well(this is not very probable since cars will still run when they are hot, even to the point of self destruction... unless one of your sensors cant handle it and screws up at that high of a temp....)

if the overheating and stalling are truly not directly related, your problem could be many things, my 91 integra had the same symptoms you describe for two seperate breakdowns.

#1 when the bearing started going out in my distributor. (if you pull off the distributor cap and see what look like graphite shavings in it or see actual damage to the metal connectors this could be what is going on.)

#2 when the ignition switch wiring harness went bad. (if this is the problem your entire car would shut down when it dies, just like if you turned the key to the OFF position, because that is actuall what is happening inside the bad switch. your dash lights, radio, and anything electrical will not work if this happens)

I dont think i nor Anyone else can help you diagnose this problem over these boards. this will require hands on work. I really dont know what else to suggest. but i can leave you with this...

#1 If you discover that the motor is actually overheating when these problems occur(despite what the gauge says), then you have a cooling problem, if you fix that and it still stalls go to #2

#2 if it is at normal temp. and still stalls it could be a lot of things but like I said before, if the motor can go back to normal, then the problem is probably electrical or in the fuel system.( but you might check inside the distributor cap like mentioned above just in case , because that particular problem can come and go during the process of the bearing eroding away)

#3 these problems will require someone to physicaly work on the car(testing the sensors and fuel system) maybe your mechanic just made a mistake and can help you more the second time around. (now that he knows it is not the thermostat)

sorry we couldnt help more, let us know what you find out!

PS there is a lot about honda's motor systems that i dont know yet, so dont believe that my suggestions are the only answers.