Daza, while you're in there it might not be a bad idea to examine the relay closely associated with the engine management system (Marked '109') as well, as those type '109' relays are notorious for causing strange/intermittent running/starting problems across the whole VW group Tdi range. If you're already groping around under the dash anyway, it will only take a few extra minutes to check.
The solder around one or more of the PCB connections in the '109' relay gradually fails - typically, you get a neat circular crack around the soldered pin or part. It's possible to resolder the broken joint but best to replace the relay anyway as the relay's switch contacts will most likely be blackened/pitted with age.
I've just discovered this exact
problem on my '01 Arosa Tdi after several months of intermittent - what appeared to be - fuel starvation problems (and on one occasion a sudden oil pressure warning light / engine stoppage for no reason).
No problems since changing the '109' relay.
I replaced the tank fuel pump control relay as well (marked '167') but the original was in perfect condition, as it turned out.