Hi there,
Well i still have the NGK R BKR6EQUP and they will probably clean up. I'd guess the missfire and crappy timining would account for the fouling so they are probably ok.
Howver i just went for a punt on the BKR6EIX iridium ones as they suposdily produce a better spark and cope with LPG better.
The 11 moniker is for bigger electrode and wider gap, so steer well clear of those. Not sure about the specific LPG ones as i think they are just designed to last longer and you should get 60-100k off plugs by what i've read so, i'll skip that. £48 inc postage as the guy charges one off shipping for upto 16 !!!
http://cgi.ebay.co.uk/ws/eBayISAPI.d...=STRK:MEWNX:IT
I'll report back how it goes !
Lee