Bucking under acceleration
 

My 1996 Jetta 2.0 stick-shift has just started to intermediately skip every now and then, mostly under acceleration, and usually right after shifting from first-to-second or from second-to-third gears. I have 235,000 miles on it and this is the first sign of trouble I ever had with it. It doesn’t do it all the time, usually when the engine is hot though. It lasts for about a second, just long enough to make the car “buck” a little. One day it will do it and the next it won't.

I changed the fuel pump and fuel pressure regulator thinking that could be the cause, but no luck. I know these “hit & miss” problems can be hard to call, but wanted to see if anybody had any ideas for me to try. Thanks!!