You might also check the throttle trim on your transmitter. Not sure what transmitter you have but It's quite possible it may have been bumped back so you will only get limited response. I've done that with my baja.
Welcome in @Jonathon , your baja instantly takes off when you hit the throttle so that tells me the clutch is fine. Adjust the mixture screw on the carb, turn it clockwise about a 1/16" at a time. That will open up your top end.