2000 2.0 vw shutt down after running 20 min

The shop needs to record the computer data on a road test
or look at the freeze frame data, when you go there

The fuel pump wasn't scoped or pressure tested

I think you need a different shop that's up to speed & knows
how to use scan tools & oscilloscopes

If it idles for hours you stop doing that & drive it for 20 miles or more

And you wonder why shops don't find any issues,they don't drive
the cars far or at all or take the test equipment along

Have the catalytic converter checked at your local muffler shop...clogged...worn out...Hope this helps.

Did they figure out if you are loosing fuel or spark when it fails to start up ? You would need to know which to proceed.

As with any no-start situation, you need to know if you have spark to the plugs, fuel to the injectors, and normal compression to proceed.

Get the crank sensor replaced. This will require removing the crank pulley-balancer to replace the sensor.

On some models, the Engine Control unit has a power supply relay. These relays some times get internal dry solder points. After driving for some time the the solder will get hot and separate. When it cools down it makes contact again. You will have to replace this relay or open it up and re- solder the solder joints. The relay is usually located on the main relay station in position 3. the relay station is located behind the right dash panel.[right hand drive vehicles]. You may need to refer to a manual for your specific model to find the exact location of the relay.

Sounds like there may be a fuel filter problem, try replacing the fuel filter. Specially if you have not done it over a while.

Sounds like a weak fuel pump.

Fuel pump or fuel filter.

sounds like a fuel pump issue.