Engine is misfiring and this will set a misfire code in the management system and set the check engine light on to flash .
This means you need to sort out this issue fast and not use the car as a misfiring engine can damage the expensive catalytic converter.
First you need to check for codes this will help you track down which cylinders are missing .
So if you get a code P0303 or P0304 then you have a misfire on cylinder 3 and 4 so these two cylinders need checking .
Possible cause for misfiring engine :
Spark Plugs .
Injectors . (fuel pressure ,bad injectors )
Coil pack or coil boots .
Spark plug cables .
Or a mechanical issue , valves ,low engine compression ,timing out of spec ,catalystic converter blockage .
As you can see there are a few things that could cause this issue .
If the car has not been serviced in a long time then start with a tune up and do a compression test so you know what condition the engine is in .
Then if needed please get back to me with the reply button, and not the poor or bad service, this way i can get back to you or suggest another expert if needed.
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Kind regards Greg.