I've had this problem for a couple years now and it hasn't ever gotten worse or better so I've just dealt with it because I have no idea what the problem is. I don't know a ton about car parts and issues so my family "mechanic" has done a ton of work on the thing trying to find the problem with no luck. I know he replaced a couple sensors and all the spark plugs and wires and checked the fuel pump and some other things and we didn't change the coil packs because he checked them and said they were good, but basically I'll start the car and it will start up fine without much turning over but the revs will bounce above 2k and below 1k back and forth until it turns off. I turn the key again it starts up fine but does the same thing until it dies. I can fix it by giving it a small amount of throttle until it rests at normal idle and I won't have anymore issues until I need to start up the car again. It doesn't do it every time I start the car, it seems like if I've been driving all day making multiple stops then it's more likely to do it than on a cold start, the engine has probably around 75k miles on it, if anyone has any idea of where I should look next I would appreciate any help.
