A couple things Tom and Ray potentially missed in this call is that in the 85 model, and both have to do with the fuel tank.
The 1985 Golf, which was the first year for this generation, has a plastic tank. Likely any rust or debris in that tank would be from the stations.
Also, the 1985 has a tank in the fuel pump. I found this out shortly after I got mine. I ran out of gas (or so I thought) and the previous owner told me he had replaced the fuel pump but he thought the gauge was off. I was looking and found a reference to the in-tank pump. After I replaced that, I had no fewer problems.
Also, no mention was made to whether the fuel filter had been replaced. I would have problems after letting my car get too low on fuel that were caused by the “crudification” in the fuel filter. The car would stall and be extremely difficult to start shortly after fill-ups. Once it had been running a while, it would apparently shift the crud enough to run fairly well. New filter and the problem went completely away.
I’ll bet the problem was casued by a bad in-tank pump.
I bought a new VW Golf in 1986. Loved the design and function of the car but didn’t like the way it was always one thing or another requiring fixing. In 80,000 miles three different relays in the fuse box had to be replaced, including the one that drove the fuel pump. So when dealing with a VW my money says to check the relay first.