Why does my car die?

Ok. I'm really new here and I've read all kinds of posts but none seem to address my exact issue. Forgive me if it is a repeat though. So, I'm driving down the road and the RPM's just drop to zero. All electronics still functioning. Pull over and try to restart but it appears to get no fuel. If I pull the mickey mouse clip off the fuel filter remove and replace the "T", it cranks back up and runs for an indefinite amount of time. It has happened like this 4 times now and I'm dreading it happening when I am passing on a two lane road or getting my tail rode close at 70mph on the interstate. My 99 MK4 Jetta TDI has 330,000 trouble free miles. I change fuel filters, oil filter, air filter, and tranny oil as often as is required. I commute 75 miles each way every day and get about 625 miles out of each tank. I do fill to the brim and let it go until almost empty. I notice bubbles in the clear fuel return line from the filter and that is what prompted me to unplug and replug the "T". It has the original lines and clips. I found a hose clamp that fit in my toolbox and put this on hoping it helps as I'm thinking old clamps could be the problem, but wouldn't it just run rough or slow if it was sucking some air around the filter. What would cause it to die completely and not restart until letting air in the fuel filter? Please help if you can.

First off welcome!

The bubbles are they large or a small stream?

Do you know if your 109 relay was ever replaced with the newer style?
Old style was black newer style is gray.

When this happens have you ever tried to restart it immeadeatly? Do you notice if the glow plug indicator comes on momentarily, this is for relay 109 troubleshooting.

pretty small stream. maybe the size of bb's or slightly smaller but steady for sure. The reason I wasn't suspecting the relay because every time the immediate fix was removing "T" and replacing so that made me think it wasn't electrical. If or when it dies again I will look for the glow plug light and I will check right now for that relay. Thanks.

ok so glow plug light sometimes does and sometimes doesn't come on and when it does come on it is off in the blink of an eye.... Relay related?

The GP (wait to start indicator) should ALWAYS come on for at least a second or so as the system tests itself. If it does NOT come on for that very brief moment, it probably means you have a relay 109 beginning to fail.

Random engine dying as if running out of fuel can be from the pick up tube on the in tank sending unit developing a split or crack in it. When fuel gets below the level of the crack, the IP sucks air instead of enough fuel.

Replace the 109 relay!

ordered a relay online from someone that swears it is only for Mk3 jettas. I am hoping he is wrong. Relay should be in today or tomorrow. I have noticed it goes on the fritz whether I have a full tank or a near empty tank and it does it at any speed. Still what puzzles me is it don't matter if I wait ten minutes or ten seconds, it will not start back up until I unplug mickey mouse tee and reinstall. How does that relay know that I have done that? The glow plug light comes on perfectly when I have done it as well. How can my electronics function properly after I unplug a fuel line? Its puzzling the crap out of me.

Any updates on this? I'm having a similar issue and am curious about all possibilities.

Have you replaced the o rings on the tee, or the tee itself? Seems to me, the o ring is getting hard/losing its seal, and re seals when you re install the thermostatic tee. My newest jetta kept dying almost immediately after startup. I found a TON of small bubbles like you found. Replaced the tee itself, with new, lubed o rings. Most of the bubbles went away after the new tee. I still didnt like the idea of the bubbles being there. I drilled out the check valve in the fuel sending unit, and it made all of the bubbles disappear. Seen it personally on 2 tdi's. More importantly, the starting/dying issue is GONE now!