After engine replacement all of a sudden the engine just shuts off?

It sounds like the throttle actuator, or the accelerator position sensor is bad, but can I ask if you have a check engine light on? We should run the codes to see if any are stored, this guide can help:

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Here is how to change out the throttle body and accelerator sensor in case a code comes up for either one. Check out the images (below). Let us know what happens and please upload pictures or videos of the problem so we can see what's going on.

Thanks for your quick reply, Ken. I have shared your opinion with my mechanic and have asked if the engine light turns on, I will keep you posted once I hear from him. By the way I'm from Australia so the time zone differs, and my reply time might differ. Just letting you know and thanks for helping me out.

Hi Ken, the engine light does not turn on just now my mechanic confirmed.

Hi John,

Even though the check engine light is not on it could still have codes, did the mechanic scan for codes anyway?

Hello,

Has the mechanic carried out a CAN scan to see if any DTC are recorded in the ECM?
Not all DTC will cause the engine check light to come on.

How to:
https://www.2carpros.com/articles/can-scan-controller-area-network-easy

Also, I would suggest checking the coil pack connector.
While the engine is idling wiggle on the connector and ground wire, black wire.
See if the engine will cut out.
The ground wire, black wire, is bolted to the cylinder head just underneath the coil connector. Check that the terminal is clean and secure.
This problem will not set any fault codes.
Wiring diagram below.

A pdf
https://static.nhtsa.gov/odi/tsbs/2016/MC-10112283-9999.pdf

Cheers, Boris

Thanks for the suggestion Boris, my mechanic hasn't checked it yet, I'll keep you posted with updates.

Hello Boris! you nailed it. Coil pack was blown. Once it was replaced with a new one, it's thousand times better, but still there is a small lag or skip in the engine. My mechanic is looking for other faults in the engine. Will keep you posted with updates!

BORIS K is one of our best! Thanks for letting us know, we are here to help, please use 2CarPros anytime.

Hi Boris, my mechanic has fixed the engine and now the engine light on the dashboard glows. But, when the vehicle is idle, stopping in traffic lights or stopping in round about it struggles for pickup and stalls a lot and stops sometimes. Do you think reprogramming the engine would fix the issue or please shed your expertise?

Sorry, we only handle one problem per thread, please post your new question here, you must be logged in.

https://www.2carpros.com/questions/new

Cheers, Ken