hi have a 2001 beetle 1.9 diesel. Sometimes after driving about an hour, mostly uphill I live in the mountains, the car loses power, will not go more than 40 mph, 60 to 70 would be normal. After cooling, few minutes, car drives fine, is this a turbo issue or what? No indicator lights show up, no smoke apparant out the exhaust pipe, anybody have an idea?

 

Can't be sure, but it sounds like a cooling problem to me, check
out the radiator to see if it's clean and air can flow through it, you
might be sure it's toped up with the correct antifreeze mixture, too
much antifreeze and not enough water in the mix will over heat, go
by the directions on the antifreeze jug , a over heated engine will
loose power and finally kill the engine to a point of overhaul.