Other Fuel System Related Problems of the 2001 Hyundai Accent

Other Fuel System problem

My car engine will rev up on its own when in neutral (I have a manual transmission) the engine revs up then idles low as if it is going to stall. I have taken it into the dealership 4 times, and they have replaced the coil pack, spark plugs, and a sensor. . . Still the problem persists. Every time I take my car in they tell me that my spark plugs are misfiring and that I need to have them replaced and because they are a wear item and it's going to cost me. I can't afford to have it done in the dealership so I did a home repair and replaced them myself. This is the 3rd set of plugs on this car and they are now misfiring again (only after 5 months) I took it to the dealership, and they claimed that they can't fix the problem because they aren't Hyundai plugs (which I understand), but there has got to be some reason that the plugs are fouling out so quickly and no one will investigate the problem. I should not have to replace my spark plugs (wear item or not) 4 times in 2 years, nor should I have to twist the dealerships arm to do the job that they are paid under warranty to do! I am disgusted with Hyundai, and the poor customer service their dealers provide! I will never buy Hyundai again or recommend that anyone else purchase from them!.