Flashing check engine light?

[hampsterzone]

First things first. I have had the plugs and spring caps replaced recently. I run 91 octane fuel, pretty sure there is no water in my fuel. Just changed the fuel filter, oil, and antifreeze w/ flush. Tranny has been flushed recently w/ new filters. I do not have a programmer installed, it will be back on Friday. My check engine light flashed or flickered for a few secs but did not stay on. I was going up a slight hill and could feel it kind of hesitate. It did this twice but the light just flashed but did not stay on. It has did this before without the check engine light being involved. Pretty much on the same spot of the highway. Any clue as to what it could be? I was thinking maybe coil pack but I really do not know. Please help! Thanks in advance.......