If you are loosing power when you start driving, I would defiantly say it is the timing belt. Sounds like your belt stretched and it wants to jump 1. I would say, if your timing belt is easy to get at, take a look at it yourself, for instance, to get at mine, I have to jack the car up, put it on stands. then undo the motor mounts, jack the engine up, take of the motor mount on the body itself and the mount off the engine, disconnect the A.C. Take the belt tensioner off, Take the tire off, and finally take the pully off to get at the timing belt. Its worth it if you actually know that is the problem. But in your situation, you can't be sure. The best thing to do is take it into a mechanic and get them to diagnose it . It's going to cost you a bit, but it might be worth it.