I haven't experienced the troubles you are with glow plugs in my B5. Having said that, I find that my B5 is very sensitive to idle gap/LSN adjustment - two stage idle and/or does not like being a bit rich or a bit lean on the idle. (IMO less forgiving than other engines)

When I get the idle fuel and gap right (the key for me was correct idle gap) she'll reward me with a strong consistent idle. Get it wrong; she'll fuel up, go two stage, or i guess it could do a plug.