My 2007 Forenza suddenly began hesitating between 50 and 60 mph @ roughly 2200 rpms, so I took it to my regular shop and they said the only codes thrown were for the o2 sensors and they couldn't get it to do what I was saying it was doing, but were emphatic that the o2 sensors couldn't be causing that kind of problem. So I took it to autozone, they did a diagnostic and these were the codes thrown: P0133, P0138, P0131, P0124. The check engine light is not coming on BTW. So I took it to a second shop, they also thought that the O2 sensors couldn't be causing it, but they said it was surging, not hesitating, don't know what the difference is. Anyway, they had it a long time and then they said that they checked online and were told that the O2 sensors could in fact be causing the problem. However, they wanted to charge me $500 to replace the O2 sensors and since I've already done research on this I knew I could get the sensors from autozone for $200, so they are wanting to charge me $300 in labor? Anyway, my question is, can the sensors be causing this issue, it feels like the car is hiccuping and it doesn't do it all the time. If so, I will go to shop number one, they have always been fair with their pricing, but they couldn't get it to do it when I had it in initially. Thanks for your help.