@stonesaint.................
Basically there are only two thing which can cause these kind of jerks, 1. Current, 2. Fuel
So if you dont feel any (not even minor) jerks on petrol, means the current is ok, now the flow of fuel from your regulator to carburetor is restricting.
Better you should visit Automax, Mr. Rizwan (Kkoool), so he will check the issue for u in ISB.