Engine shaking and stalling?

I have a Toyota 1993 corolla 1.8 litter, 143000 miles.
I bought the car for 4 years.
In Feburary. One time when I was driving, I felt the engine shake when I stop at the red light, and later the car at 10 MPH, the engine shake again and the car stop running.
So my friend help me to change the spark plugs, PCV valve, rotor. The car run normal again.

In April 10th, the engine shake again, and the car stop running, and won't start again. So my friend help me the change the distributive cap with a set of new wires.
After change the parts, the car start and run, but the engine still shake a little bit. I ignored the problem and keep driving until two days agao 16th, the engine shake whenever I stop the car in front of the red light, and finally, it shut down itself while the engine shaking when I stop the car at a stop sign for 5 seconds. I could start the car, when the car is in parking position, nothing happen, but when I shift to D, forward, the engine shake, then I accelerate, the engine stop shaking, and the car run normally, but if I stop again, the engine would shake again. So right now when I stop in the red lights, I have to shift to parking mode.
What's the problem? Please help. Thanks.
By the way, I change the timing belt last year 2005 in August.