when I crank up my car it'll skip, i'll see the rpms going up and down and the car almost seems like it's going to cut off but it never does. I can drive it for probably about a min and it'll stop. it only skips when it's idle. I don't think it's a gas issue because if it wasn't getting a steady amount of gas, the rpms should drop below idling for a second or so but this mostly stays above 1000 rpms when it does it and it idles around 750. it only happens when I don't drive it for a day or so. I can drive it and then park to turn it off and come back a few hours later and it won't do it at all. The mechanic told me that it just needs a tune up because a couple of the spark plugs are misfiring but i talked to somebody else who said that if a plug is going out, that it won't stop when i start driving it, it'll keep on doing it no matter what. i don't know who to believe and I don't want to pay over 400 dollars for a tune up if it don't need it. any help would be great! it's a V6 if that matters. thanks for the help!