I have a 94 Mark VIII, I was at the bank yesterday suddenly the car started to run a little rough, I gave it a light rev and held it for a few seconds and let go but it didn't go away. Then when I was done I looked down and the car was idling at 1500. I put it in drive and drove home when I got home I put it in park and the idle was varying between 15 and 1800. I couldn't find any vaccum leaks. This morning I started the car and it idled around 1500for 5 mins and then it stopped and has been fine since. The IAC and EGR are new and shiney does anyone have any ideas?