So I will make it short, I am having problems with rough idling, When i start the car it runs rough ,kinda sputters untill 15 or more minutes of warming up, it still runs with a less than great idle but the sputtering isnt really noticible after the 25 min warm up. Occasionally if you stop hard then hit the gas quickly or accelerate quickly from dead stop to make a turn u hear a knock sound (like when you are running outta gas(piston slap ?) My questoin is are the two issues realated , and can either one being doing perminant damage , ( She has no acceleration problems of any kind at ne speed , with the exception of sluggy performance for the first 5 minutees after the car has sat for more than 4 hours. thanks , p.s not looking ot fix at the time(unless critical. just dont want to do further damage , she is my baby , runs great on the freeway at 75 mph. thanks .