i have a 98 prelude when i'm on idle car heats up alot almost to the top but when i start driving the temperture goes back to normal?

 

Has to do with getting air over the radiator. Maybe your fan is broken? I am no pro.

 

My car did the samething, but it was only when i ran my a/c, it was due to a short in one of my fans so when id sit at a light it would heat up, then drop when i drove. so if your running ac check your fans....

 

Check the Radiator fan, A/c Fan, And Coolant levels

 

how do i kno my radiator cap doesn't work?

 

mine was doin the same thing, but i opened the hood and it wasnt hot and soon to find out i had a loose ground

 

sounds like you have bad air flow through the radiator, more like you fan is not working, very easy to test, just unplug the fan and hook them up to the battery, if it works you will hear it move, just don't put your hand in the way...