Was hoping for some guidance here. I searched the 'net for info and followed what sounded like a hopeful solution, but no dice. So now I’m giving it one last shot before having the car towed and paying a mechanic to find out what is wrong.
Here is the situation: I have a 2002 VW Beetle 1.8L Turbo with over 120k miles. Recently it started idly roughly on occasion and had a slight rattling noise but only when stopped. When it was driving, it felt fine. This went on for about a week and then one day about a week ago it started for about 10 seconds and then stalled. Since then it will turn over, but not start. We’ve checked the starter, fuel pump, fuel pump relay and ignition coils and have replaced the crankshaft sensor (which was what I found on VW sites as saying it often solved problems like mine). The battery is new. Part of what I saw when researching was in addition to what is currently happening other owners had a long term issue with the car bogging down once in awhile at high speeds (50 mph+) for a few seconds and then picking back up again. My car did this as well and that’s why I thought the crankshaft sensor may be the issue. Any advice would be greatly appreciated.
This particular motor has a rather complicated internal cam chain tensioner. (before I get flamed, yes, it has an external belt, this one keeps the adjustable cams in time). This tensioner can fail, cause a bit of rough running and what sounds like rattling inside the engine, especially under low RPM’s and heavy load (like, say 4th gear, at 20MPH, and you put your foot down). Almost like pinging, but not.
I can’t diagnose it over the 'Net, but this part may run ~$600 (there are a couple different ones, $600 is the expensive one), and replacement labor will be about another $600. The top of the motor needs to be ripped down to get at it.
I don’t know for certain this is the problem, but it’s one possibility. Wish I had a better idea for you, and i hope this isn’t the issue, for your wallet’s sake.
Oh boy, Chaissos, I hope you are wrong. At this point the car is going to sit until our next payday, but a $1200 cost would basically put us on ramen noodles for a few months. 
I also have a message in to a friend who knows cars far better than anyone else I know personally. Hopefully he may be able to give some good advice as well. I forgot to add above (since I’m sure someone will want to know), that yes, the check engine light was on and no, I can’t currently check the codes. I’m going to ask mechanic buddy as well if he has a portable scanner.
When was the timing belt last changed? It might have skipped a tooth or 2 and thrown the timing off. If you get the timing belt done, change the water pump while they’re at it.