rough idle, stalling issues

[Noodle Boy]

Hey guys,

Just a question on behalf of a friend who owns a Yaris. The car is experiencing rough idling, and by rough my friend means fluctuations up to as high as 1500rpm to as low as the point of stalling. This symptons occurs occasionally. The car has been brought to various mechanics. One diagnosed it to be an alternator issue and has promptly replaced it with an aftermarket one. Battery is still strong, as the new alternator is charging it properly. Another mechanic found an error code through the ecu and resetted it to clear, but popped up again recently.

Where I think the problem is coming from are:

-dirty throttle body

-bad injectors

-ignition system, ie. Coils and spark plugs.

-fuel pump.

The car has recently ticked over 100k km and is a manual. What does everyone think about this issue? All suggestions will be of value to my friend.

Thanks all.

[Muz bar]

Well i think your probably on the money with injectors or spark plugs.

Check the spark plugs first then leads.

Put some injector cleaner in the petrol.

Could the car have overheated?

Lossing pressure with gasket damage.

[Noodle Boy]

I doubt it's compression related. He says the temperature needle remains in the middle when it has warmed up. I'm pretty skeptical of injector cleaners as a whole.