1995 jetta stalls randomly

The problem started when I was driving down the highway and all of the sudden when I was accelerating my car started slowing down, and when I would try accelerating more the car would slow down more, and the only way to get it to actually accelerate again was actually pumping the gas, then it would catch and speed up again. The car did that like 6 times that day, I almost thought I wouldn't make it home. Then after that I thought it was the fuel filter I changed that and, the car seemed fine. A couple days after that the car did it again, but at a lot slower speeds so this time I couldn't fix the problem by pumping it, it now would just stall. I took the car too a V.W. mechanic place, and they checked the check engine light, and thought it was the speed sensor, they put a new one in it and after that the car seemed fine again. Then 2 days after that it started doing it again, really bad, now the car only seems to run for about 10 to 30 seconds at a time. I took it back too the V.W. mechanic and he drove it and of course the car didn't stall or have any problems the whole time I left it there. He thought it could have been the idle regulator(I think that's what it's called), he told me the next time the car tries to stall again to unplug the sensor from it and see what happens, he said if I unplug it and the car runs better then that is the problem, and if the car runs worse then that isn't the problem. It happened again,and I unplugged it and the car ran worse and stalled. So I am really confused, Does anybody have any clue to what it could be?