I have a 94 Intrepid with a 3.5 ltr engine thats been acting very strange lately. For some reason whenever I place it in neutral, the engine sits idle at over 2000 RPM. Usually it stayed around 1000 RPM which should be normal. What would cause this sudden spike? I've also noticed that whenever I'm driving, the car will very slowly start to increase in speed all by itself. What would cause this and where should I start to look when troubleshooting?