1993 Other Mitsubishi Models Car jerks sometimes

The cars is good, but sometimes it jerks while I am crusing. It usually happens when I rev up a bit, but the problem is not replicable. Its like the engine doesnt get any power or fuel and then suddenly it does. Usually such things happen when you are trying to learn a manual car. Put it in the first gear and if you dont let go of the clutch properly it jerks right. The same but while cruising. I went to firestone for engine diagnostics and they couldnt replicate the problem, but they did say that I have a different air filter installed. Any suggestions?
Earlier I thought maybe some problem with the fuel.

Can there be a problem with the transmission?