throttle sticks!
 

I have an ofna ultra mbx pro and the throttle sticks. Its not the reciever or the servo what else could it be?

RE: throttle sticks!
 

take off the linkage from the servo and the arm on the carb. Try to move the carb by hand, and try giveing it throttle with the radio. This will eliminate problems with carb and servo

When all is together make sure nothing is binding

it could be interfearance or your car went out of range. Do you have a failsafe?

You didn't give enough info. Be more specific and post video