Bad jerk help!!!

Hi all Golf MK2 Owner. I had early version Golf MK2 run with EV 1.8 C.I.S K-Jet system, i have bad jerk when engine hot. early morning starting everything is good nice revving, i was driving the car in the morning to work, is 80km far from my home. so when engine was cold i can step hard on the pedal and speed can go for 140km/h on the highway no any jerk, run smooth. when get traffic jam or in the town temperature get slightly hot i step hard on pedal then bad jerk, no power and like misfire. (The jerking feeling is like someone on the back banging my car and whole dashboard vibration). if i gentle step on pedal is ok can smooth and go. i not good in this system need all your guys share some information and suggestion any direction to work on it. Thanks.

 

Check for vacuum leaks, fuel pressure, possibly a sticky plate in the CIS/K JET metering head?