I'm driving a 92 Prelude Si 5 Speed with no modifications, with 127,000 miles. Only recently, when I shift the car into neutral and let go of the gas completely, the rpm's drop to about 200 rpm, then it will go up and down from about 700-900 rpm's. The problem only occurs when the engine is at normal running temperature. My only recent repair was to replace the seal behind the oil filter. Any info would be appreciated. Thanks a lot in advance. TI