Apparently, this is a "batch fault" with the 2001 GSX-R1000's.

My throttle position sensor (TPS) started failing at the start of the year (2005). I blamed it on poor tuning, bad fuel, cold mornings, bad suspension, bumpy roads and bad riding etc. After a thorough tune-up at 30000km (and to no avail), I got a tip off from JeffW of gixxer.com (thanks a million mate !, you're a bloody legend ;).

The TPS has a funny style connection to the throttle drive.. So the throttle drive can only apply a turning force to the TPS shaft in one direction only. The TPS shaft therefore relies on a spring to return it to its rest position. What happens is that the "o-ring" inside the TPS swells up. When the throttle turns the TPS shaft, the TPS shaft will not spring back (see o-ring pictured below):

The bummed output voltage of the sensor seems to confuse the ECM (Electronic Control Module). When I closed the throttle, the ECM still thinks you have it open, therefore it cuts the motor (Nb/ I didn't analyse exactly what it does. whether it cuts the ignition or cuts the injectors: one of the two anyway).

These were my symptoms (and common with this fault):

I rang up Peter Stevens (the local Suzuki Dealer), and they wanted $180 for a replacement TPS (2005 money). I nearly chocked when they told me that.

Electrically, The TPS is a 5K ohm linear variable potentiometer. Dick Smith sell "Pots" for about $1.60. If you want a good quality one, then Farnell sell them for between $10 and $60:

http://uk.farnell.com/jsp/endecaSearch/searchPage2.jsp?Ntt=5k+potentiometer&newSearch=true&Nto=potentiometer&Nty=1&showImages=true&N=401&Ntk=gensearch

As a temporary fix (and to verify the fault), I repaired my TPS. Basically, I removed my TPS from the throttle body. Cracked it open with a stanley knife, identified the problem, removed the o-ring, and glued it back together (epoxy resin). This fixed fault.

Here are some pics of the finished hack: