Car trouble.

Hi there,
I have some trouble with my 1995 hyunday exel, 5 door, manual.
It plays up when I drive by stottering when I accelerate, and the engine light coming on and off. I have taken it in to garage and it came up with 3 codes including the air flow sencor which they replaced. The other code ended up being a broken key of the balancer thing(hope you know what I mean). The replaced that and told me to replace the balancer thing. The car drove like a dream untill I had it back for nearly a week, when it started stuttering more than before and the engine light being on permanenly. So I booked it in to get the balancer replaced and now I've been told that the problem is the air flow meter, cost price $465 retail. Obviously I know only how to drive a car and am wondering if I am being stuffed around and if fixing this will lead to a happy and healthy car or more possibilities of this problem. I hope you can give me an idea of what the problem might be. Thanks for your time. Miranda