The car ticks over fine when cold, and then after driving and warming it up, coming back to a stop it idles perfectly it seems at around 750/800rpms.
However, if I rev the car the idle drops significantly below 750 to just a little less than 500 for a short while, then picks up to 600.
Sometimes it will pick up and drop by itself to below 500 and to 600-750..Surely my car shouldn't be idling this low?