Volkswagen: 1998 TDI Beetle Stalling, fuel injection pump, fuse panel

Question
QUESTION: Help!

I own and love a 1998 TDI Beetle, manual transmission with 169 000 kms....For four years now it has been stalling and VW cannot figure it out. It will stall in 2 scenarios but does not happen all the time but tends to happen more often when the gas level is half a tank or lower:

1. Pressing the clutch in to down shift or move into neutral to coast.  Battery light comes on and car will turn over no problem and off I go.  This is the most frequent one.

2. Down shifting at higher speeds on the highway and no acceleration when gas pedal is applied.  No pick up and eventually battery light comes on as above and again the car with turn over no problem.

Help!!!!

ANSWER: Hello tara.  Based on what you said,...I would have said it sounds like the tandum (sp) pump is dying.  However,...I don't believe your model year has it.  (going off of memory here)  The cheapest and easiest fix to try is the 109 relay.  If you do a search for TDI 109 relay you should come up with plenty of results.  The fuel info you have is what kind of throws me off...but the two biggest problems I have seen are the electrical part of the ignition switch failing and the relay.  Personally I would replace this relay and go from there.  If you look in the fuse panel, you will see the relay with 109 printed on it.  This is the one you will be replacing.  It is the ecm power relay.
let me know what you find.
thanks,
shad

---------- FOLLOW-UP ----------

QUESTION: Thanks for the response....I have done the relay 109...Also the MAF, O2 Sensor, glow plugs, all the dealer recommended things...they are lost at this point....any thoughts on the fuel/injection pump or any tie into when the clutch is depressed.....

Answer
well,... last thing that I found: an older TSB/Recall at work today about a wire harness under the battery tray that gets chaffed and shorts the ecm wire and the fuel pump wires...  it does say that this can cause stalling... but no info on the clutch bit.  
 Tara....honestly if this was a gas car,...I would say you are loosing your idle adaptation log and the car was stalling out due to this.  I can't say if tdi's have this our not because i haven't seen an older one in too long.  (we don't sell a ton of these in south carolina...not sure why)  But I want you to try the diesel forum on vwvortex.com.  I hate getting stumped on questions but unfortunately without being able to put my hands on this little beetle... I'm stuck.  Good luck with it and please don't hesitate to send me a note on anything else or to let meknow you have solved the problem.  
many thanks,
shad