Newbie needs help with bucking '92 Jetta

Okay. I don't know what the hell I'm doing with cars. But I took my Jetta into the mechanic here in Mexico and have had it returned 2 different times, having been told that it is fixed. Well, it continues with the same problem. So, I'm trying to educate myself. It idles fine, but when you press on the gas pedal, it sputters and dies. When you are in gear and try to advance, it dies unless you give it the full pedal of gas (revving the engine horribly). Then it can take off to a jerking, bucking start and can keep going if you constantly give it a heap of gas. There is NO power. I changed the--well I don't know what the hell it's called--it's attached to the air filter by a hose and another hose feeds down out of it. It has a filter in it as well, regulating something with the oil (now you see why I have to educate myself!!) and the filter had become detachted and gotten stuck in the hose leading to the air filter. Therefore it was leaking little bit of oil, from the pressure created by the clogged up hose. It is a Mexican car, and I don't know how they would be different in equiptment, but it has a 1800 90 CP motor. It does not have fuel injection. Any ideas, with that scant bit of info?

When was the timing belt last changed? The engine has a camshaft that opens and closes the valves at the right time. This shaft is mechanically linked to the crankshaft by means of a timing belt. It is possible that this belt has slipped (it has cogs..teeth) and that the timing is now so bad as to prevent it from running properly.

Yes, we changed the timing belt. It's been a mystery, to the point where I ended up just going to get my car after a week, without it being fixed. The mechanic said that he worked on it for the last two days of the week straight, but couldn't figure it out. I took it to another one, and this is something that might be relevant. He said that there were two valves(?) that regulate the amount of gas that is being sent to the engine. One comes into play when a little bit of gas is needed, and the other, when the gas pedal is pressed down more considerably. I have noticed that when I just ride the pedal a little bit, the bucking doesn't occur as much, or sometimes not at all. Can anyone tell me about these valves (that may not be the right word... he was talking to me in Spanish.) Thanks!!

I just replaced the button in the distributor of my Jetta and solved a similar problem. It is a $13 part from VW and your mechanic can change it in 10 minutes. I wonder if in your car the button appears okay but the noise suppression resistor is intermittent.... Worth a try...

In any case it is a problem of fuel or spark. When you start the car does it smell badly of unburned gas? Probably spark...ignition problem. Does the car always have this problem or only when it is damp outside?

Thanks for your thoughts. I have taken it now to a record 4 mechanics, and nobody can figure out what is wrong. I tried to look up "distributor button" on the internet, and couldn't find anything. What else is that called? The distributor cap has been completely changed since the problem started, and that hasn't helped anything. The exhaust does smell more than it should (and used to before the problem). It doesn't exactly smell of unburned gas--could it be maybe that the gas hasn't burned well (thoroughly?). I don't know how the car acts in damp weather, because for the time being, it has been warm and dry here in Mexico. I have considered that the gas is just not clean here in Mexico and put in an additive, but that hasn't helped. I couldn't find anything about "noise suppression resistor" either. Thanks for your ideas. Let me know, if you can, about any other names that the button and noise suppression resistor have so that I can further investigate.

I tried to look up "distributor button" on the internet, and couldn't find anything. What else is that called?

It's called the rotor, and it should have been changed with the cap. Make sure it was. What about the plugs and wires?

You have two fuel pumps, the main one under the car and a supply one in the gas tank (access in trunk under carpet and ametal plate). If the one in the gas tank goes and the tank is fairly full you will get the symptoms you described. To test, detach the gas line that has the out arrow on top of the pump and stopper it with a phillips screwdriver. Attach a plastic line to the pump outlet (where the gas line was connected) and run the other end into a (approved and empty) gas can. Turn the key to the on position, but don't start it. A fair amount of gas should flow into the gas can. You can disconnect ignition from the starter (quick disconnect) and turn the key to the start position and it will allow the pump to run with out turning the engine over. If the supply pump works, reconnect everything and have someone check your fuel pressure.