First of all, you should SLOW DOWN. This sounds counter intuitive, but you have to. Don't even time yourself at first. It is impossible to improve on mcat verbal if you cannot get answers correct. Slow down and get 95-100% of the answers correct FIRST, THEN speed up. At that point, start timing yourself, and whittle down your time by not rereading the passage. The only time you should reread anything is to find a detail that questions asks for. Otherwise, the rest should be scanning the passage and going off of your circled important words and any symbols you use to signify main point, change in direction/topic, specific detail, etc. And as other posts have suggested, just keep doing practice questions. I am part of the school of thought that general interest reading is very important for improving, accuracy, and precision. If interested, go read some of my threads under "more mcat advice", however, remember, many have differing thoughts about reading general interest for the MCAT. Good luck.
sscooterguy