AssalamAlikum my dear pakwheel fellows 
I have a problem with my Suzuki liana. It's really a headache, when the car is on idle its rmp needle would drop below 1 and engine would stop, when running on CNG.
On the other hand, if the car is on idle and the engine is running on petrol it's rmp needle would continuously go to 2 and then come back to 1 and then again go back to 2 and come back to 1 and it won't stop doing this. On petrol, if you are crusing on low rpm it would eventually slow down and at same moment it will give you a jerk and come back to its original speed. Consider it like you continuously push and release the throttle on the first gear.
Kindly suggest me a solution to this problem and I will be very thankful to you.
P.s: It a 1.3 dohc engine (picture attached) recently changed to japenese one as its original engine gaskit was burnt. And this problem started after changing the engine.
Secondly, I was wondering that, is liana and swift engines same? They both look same. If they are same then why swift is smoother and quiter compare to liana ?
