on start ups it goes up to 2000 then quickly drops down to normal, then the other day i got off the highway and it started reving up to like 2500 then droping to like 200 rpm, it did this for about 3 min and then it droped so low the car stalled out, does anybody know what this is symptoms of? also in first and second gear sometimes when im just letting off the clutch i get this like squeeling noise that last only for a second but it soesnt sound like a belt squeel, its more like a scraping kind of noise