I noticed the car shakes/vibrates alot under deceleration from 5 to 2k rpms. I just bought a new dash pot an set it at 2800 rpms just touching the spring loaded lever . Could it be a tight throtle cable line or misaligned dash pot? Im running a pulley no air pump and downpipe thats all.

Alex

Could it be something on the throttle body

 

are you sure it has something to do with the throttle body?