i have a chevrolet optra 2006 model the problem is no idling?
Do you mean you have to keep the revs high to keep it running? If so, you may have a gasket leaking in your fuel system and it is sending the incorrect codes to your computer. I'd have the codes read to see if they can find an issue. It may be small and simple, or it may be a mid size fix.
is this expensive to have the codes read
It should not be. If you pay to have the codes read and it is an inexpensive fix, it is worth it. I don't know the costs people charge, but you should ask if the cost is adsorbed in the fix if you chose to go that route.
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