On PSAT practice tests, I consistently score in the low 200s without time constraints. On the real PSAT, I've scored in the 150-190 range twice because I can't get to all of the questions. Most of my time issues are in the math section. What can I do to fix this problem?
The first thing you need to do is start timing yourself on every practice test! If you don't practice answering questions quickly, you won't suddenly wake up and be able to do it on test day. Get accustomed to how fast you need to go.
You should also skip questions that take more than a minute to solve. On your first pass through the math section, you'll get through all of the easy questions. Then you can go back and deal with the more difficult questions. This ensures that you won't miss out on any questions that you should have known, and you won't waste time lingering on hard questions that you might not answer correctly anyways.
Finally, memorize the formulas you need to know for the math section. This saves time because you won't be flipping to the front of the section to look up the formulas you need for different problems.