About two months ago, I replaced the timing belt by myself. Now, I find the MPG is much lower than before. Someone told me that I needed to adjust the distributor. My car is 98 camry, and I am pretty sure there is no distributor. So I am wondering what causes this problem. By the way, if I haven't adjust the timing pretty well, will it affect the acceleration?
many thanks

Sounds like the timing belt is off a tooth. Are you REALLY SURE you got the pulleys to line up correctly? It's easy to knock them out. You have to manually align the pulleys with the marks. I usually wind up checking it about 100 times before I am satisfied.

Playing with the timing might help. Just mark the distributor so you know where it started from.

When I had my Timing Belt replaced at the Toyota dealer, my milage seemed to drop for a while, too. It dropped about 5mpg. I figured it was due to a new, stiffer and tighter belt that wasn't broken in yet.

3000 miles later my milage is back to where it was before the timing belt replacement. (in a 2000 Camry, 4cyl) If I remember correctly, it probably got back to "normal" after about a 1500 miles or so.

Do a compression check. If the valve timing is off, you will see it in compression.