Car Jerking

Hi guys,

I'm driving mazda 323 protege 2003 and the problem I have is that it keeps jerking in the first three gears. Originally it was jerking only in first gear but after a few months it became worst.

I have replaced the spark plugs but that hasn't fixed the issue. What other things can I do? I would like to avoid going to the mechanics because where I live they are super expensive.

Many thanks!