Quote Originally Posted by Daox View Post
The O2 sensor is not the problem. The engine will run without an O2 sensor, just not as well and won't pass emissions.
Not to say your wrong, because 99% of the time that is the case, but my aveo would not run at all and it was the o2. Put the new one in and it ran great.

OP: Based on your brief description, I am going to say, if it only happens on highway and that infrequently. I would suspect an issue with egr, or the evap purge. You would need to see (probably with the dealer) what condition activate those two systems, but it is usually cycled on during cruising speeds after warm up. Additionally from your description, i honestly suspect the evap, as it sounds like it is depressurizing the fuel system when the system purge valve opens.

but thats just an internet diagnosis.