I have had similar problems on a VW Polo 1.2. It could be one of two things that I know of ( it could be another fault too).

The first, less likely, is a coil pack failure. Modern day engines have a coil per cylinder that provides a spark to each cylinder at the correct time. When one fails you will be running on 2 / 3 cylinders ( on a 3 / 4 cylinder engine respectively). This is unlikely, however, as usually coil packs progressively die and you would notice it getting worse over a number of days or more likely hours before it failed.

The second problem I have had, which was almost identical to your problem; my car would start fine and sometimes run without issue. After driving it for a while I may start to get slightly jerky drive, then get a severe loss of power. Turning off the engine for 5 minutes usually fixed it but there were some occasions I had to leave it for up to half an hour. There was even one point this happened queing up to a toll booth on a motorway, and I was stranded in the centre lane for 5 minutes until I could start it again.

Both errors, though, should present an error code, most likely indicating a misfire and / or post-cat emission issues.

Get your car checked at a dealer with a diagnostic machine or, alternatively, if you have an android phone you can do it yourself with a minimum of outlay. You can purchase a cheap OBD2 bluetooth adapter from ebay or similar, then download this application https://play.google.com/store/apps/details?id=org.prowl.torquefree. You can plug the adapter in to your car, connect your phone wirelessly to the adapter and check for fault codes.

If it's a coil pack failing, you will likely see a misfire registered on only one cylinder. If it's the cam sensor, you could show a misfire for several cylinders. Either way a diagnostic check will point you in the right direction.