| there are a few things. One would be a bad MAF. Another would be a vacum leak, or perhaps a few vacum leaks. Have him check all of the hoses for holes. I would think that there would be an error code if it was the MAF. I do not recall there being an error code when I had a vacum leak... but there may have been but I do not remember. If this guy is any good he should be able to track it down with out much of a problem. If it was anything else like O2 sensor ect. it would give you a code... Hope I am not forgetting anything. Good luck. | 
