Yes you're right on airtrek.airtrek 4G63 engine is also good since got high torque and 2L cheaper roadtax. easier to find parts than 6A12 or 6A13..
---------- Post added at 09:16 AM ---------- 6 hour anti-bump limit - Previous post was at 09:12 AM ----------
jerking happen due to several cause. spark plug kong, plug cable no good, running too lean or too rich. bring to workshop for checking.. AT can also cause a jerking.
Perhaps you can try a synthetic ATF. I had a jerking problem on my brother's car, the solution was just better ATF because the previous owner didn't take care of the gearbox...Yes you're right on airtrek.
On the jerking, it only happen on 3rd gear. Already sent to 3 wshop but they're unable to find a solution.