I got a really well taken care of '89 Honda CRX Si for my birthday. Car runs and looks fabulous! Only 93K miles on it too. Only thing I notice so far is after the car is thoroughly warmed up by driving 10-15 min. and I come to a stop (whether in gear or neutral), the RPM's go up and down in like 2-3 second intervals between just below the 1 to a hair above the 1.5 marks. When it is on the down side the headlights even dim a bit. Someone at work said it has something to do with Air Intake. Any ideas or suggestions? I don't want a minor problem becoming a larger or expensive problem, so would like some advice on what the issue is and how to fix, preferrably not costing me much. Thanks for any help!

 

Do you have any cell code? Usually, erratic idle is from a bad coil or distributor...

 

maybe try to clean the fitv, that could cause a fluctuating idle