I need your help people. Last night I raced my neighbor down the street in his 97' Z28. Well the first time my truck ran good, and I beat him by about two trucks. Than when we went the 2nd time my truck bogged and it seemed like it was misfiring. It seemed as if it was hitting the rev limiter, but it wasn't that. Funny thing is that it only happend from the launch till about I'd say 40 mph than it ran fine. Well I tried going out this morning and seeing what it would do, and it happened again. One of my friends said it might be the gas. I am using 91 octane, however it is from a cheap gas station. What should I do? What do you guys think happened? My truck is stock, other than the k&n filter. Thanks in advance for your help.