I have this 03 blazer 4x4 with 317k miles the damn thing runs great somehow, the transmission was rebuilt about a year ago. Here lately whenever the rpms climb to 3k+ the needle starts to go ****ing wild, it doesn't feel or sound like the transmission or engine are having problems shifting so its really a non issue, as it's an automatic but I'd like to know what the hell is going on and how I'd go about fixing it up. The transmission fluid looks good and is at a good level, the only thing I can imagine is that it's a sensor of some kind but I have no idea what sensor.