Heat blows cold and hot, temperature gague fluctuates, rough idle on startup.

SOURCE: 91 accord overheating

I have had same problem .I flushed the motor to clean the water ports inside the motor.It worked for me hope it works for you

SOURCE: 04 civic heater blows cold air at idle

you should have hot water on all rad. hoses when the motor is running at a norm. temp. the water is not going through the heater core like it should. you have cutoff valve bad low water are a stopped heater.try a hoter thermostat if none of the above are true.

SOURCE: oil leak through the distributor

why do you need to remove the filler cap when the car is running???
There is a seal around the distributor. Mark where the distributor is and remove it. Then replace the seal. Put it back together in the same location as before you removed it. It is also possible that your valve cover gasket is leaking and dripping on the distributor.
Cooling problem: Try washing the outside of the radiator where the cooling fins are. Spray it down with a really good degreaser and rinse it off. WARNING: Do NOT use high pressure because you will need a new rad after.

SOURCE: 2002 civic ex overheating

with your description it sounds like your fans are not coming on, also sounds like the problem was never solved, sounds like you threw a lot of money at your problem also... check to see if the fans are coming on at the right times, seems like a n air movement over the radiator since you say it only gets hot in stop and go traffic... well when your driving at a constant highway speed guess what you have air movement through the radiator... check also a clogged ac condensor with bugs, pressure wash it out so the air can pass through it easily... please rate my help thanks

SOURCE: Car overheats stop and go traffic, heater works over 2 rpms

I had a similar problem with 2003 nissan sentra, no heat , and car would stall on road on and off. Became a problem more frequently stalling. Took to nissan and they said it was head gasket. Fixed it and never had problem again. But i had it fixed at a local dealership since nissan was charging 1000.00 compared to 550.00. I replaced water pump and thermostat first b4 this and no cigar.