I have a manual 97 del sol vtec model. I was out of town for a bit and didn't drive the car for a week and a half, came back to a dead battery from the negative degree weather. I replaced it and now when ever I release the gas pedal and coast the RPM's will jump about 500 RPM's (instead of dropping to the ~900 RPM norm), once I am stopped at a red light the RPM's will then drop to 1.2k hover then drop back down to the normal 900. I don't know if it's caused by the new battery i put in, it's an autocraft gold battery. Any other ideals?

 

I was having the same issue. RPM high only when coasting and 1 sec after full stop. It was the IACV. I cleaned it out with diluted simple green then flushed it with TB cleaner. The simple green removed some spots of oily residue the TB cleaner didn't get the first time around.

 

Mine has a similar issues, I will have to check the IACV. Thanks GRNcivEX for the tip.