'99 Jetta TDI: Cutting Off

I just purchased a 99 TDI with 71,000 miles on it. The car has a problem of cutting off, like someone turned off the ignition key. It has cut out going 65 on the interstate and going 35 on a country road. The car will always start right back up. It happens sporadically. I might go 2 days without it doing it and then do it 2 times in a day. I took it to the dealer where they repeatedly drove the car but as you would guess it would not do it with them. They said there were no codes in the computer thus they can not fix it. I have an extended warranty but until they can figure out what it is they can't fix it. Anyone else have this problem or familiar with it and if so what was it? Help!
William

Intermittent problems can be difficult especially when it won't act up for you. I would suspect the power supply relay or the fuel cutoff solenoid. The power supply relay in under the dash in the relay panel #12 position (middle row, second from right). The fuel solenoid is in the engine compartment on the fuel pump/distributor. Since they are probably not losing power, the only way I can think of to test them is to listen for a clicking sound when it dies and when it resets. You can also feel the relay to see if it gets excessively hot.

I just purchased a 99 TDI with 71,000 miles on it. The car has a problem of cutting off, like someone turned off the ignition key. It has cut out going 65 on the interstate and going 35 on a country road. The car will always start right back up. It happens sporadically. I might go 2 days without it doing it and then do it 2 times in a day. I took it to the dealer where they repeatedly drove the car but as you would guess it would not do it with them. They said there were no codes in the computer thus they can not fix it. I have an extended warranty but until they can figure out what it is they can't fix it. Anyone else have this problem or familiar with it and if so what was it? Help!
William
Sounds like the infamous relay 109. I think they're about $20 at the dealership. Try other suppliers like www.tdiparts.com to see if you can get better pricing.