So I have a 2002 GT(roush stage 1if it makes a difference) and recently I have had a code P0401 for egr come up. It then Started to idle anywhere from 1500 to 2000rpm at times. It only idled high after warming up. It's not a rough idle it gets there and it sticks. It's so bad that the car could drive itself in second car and sometimes 3rd when idling at 2000. I checked for leaks found none so I flashed the ecu and reinstalled the custom tune. It ran fine for 2 days then started to idle high again but the code never came back. Has anybody had this problem or can anybody help me out?