Hello, my civic acts crazy sometimes. I will be sitting at a traffic light and the idle will be a nice normal 6 or 700 running great. All of the sudden the rpms will jump up to 1500 and stay there for 1 minute or 5 minutes or I will get to the next light and it will still be at 1500 when I come to a complete stop. It will drop back down sometimes to normal and stay for a little bit and then go back up again. This is totally random and drives me crazy!! It seems to do it more when it's cold out, it did it one time today, didn't do it once yesterday and it did it all day the day before that. I have replaced the iac with a used and tested one with no change. I have cleaned the throttle body numerous times, as well as sprayed 2+2 everywhere to check for a vacuum leak with no luck. I also started to notice that while cruising down at a steady speed say 50 for example. Rpms will jump up from 2800 to 3000 and stay for a little and drop back down, definitely shifting between gears. Sometimes it does this for a while, up and down or stays same for a while. My brake pedal was sinking to the floor last summer like my booster was bad so I got a new one but never had time to put it in and it hasn't done that all winter. Any help would be much appreciated, thanks in advance. Kevin