Hi, some days ago, the idle speed started being unstable. I noticed this when braking at a traffic light after driving at high speed and also when turning the engine off and starting it again; it starts with around 500 rpm and it is only after some minutes that it normalizes. The other problem is that there is a terrible smell coming from the exhaust, and also that, when changing to first gear, a strange noise is heard. It seems to be a clutch or bearing sound. Please help me. Thanks.

My vehicle suddenly stalls when driving. I've already changed the fuel pump, temperature sensor, catalytic converter, crankshaft and camshaft sensor and the oxygen sensor that is right after the catalytic converter, but still it starts, works perfectly at idle speed and, when I start driving it, it loses strenght and stalls. Does anyone know what it might be?

Why? One mechanic said wheel sensors. Another said the error codes are everywhere from catalytic converter to others.