FalconTi0

Hello all, i have a 305 carb. when it is in Neutral or park the RPMs stay kinda of high and when i put it from park or neutral, to drive or reverse there is a jerk then all is fine. one person told me (without looking) it had to be the transmission. a couple people looked at it and thought the carburetor needed tunning. I just wanted to hear some thoughts from some people more familiar with muscle cars. thanks ahead of time for your help.