Why not try swapping the left and right bulbs themselves? Given how inexpensive non-xenon bulbs generally are (I've got xenons - pricey), I'd just replace the iffy one.
How long has it been since you changed out that new headlight switch.. Maybe that new one is going out also... (Was it a Porsche unit, or an aftermarket one?)
Some stuff for sale: M030 S 24mm front sway bar, M030 base 19.6mm rear sway bar, 996 GT3 OEM Porsche Motorsport front strut mounts monoball "camber plates"
WTB: looking for some 5-7mm spacers with extended bolts