Today I finally went and got 10L of BP Ultimate 98 and bunged it in. Had the motor running for a couple of minutes on that and it wouldn't hold idle. Hmm must be a fuel pressure problem - sure enough one of the injectors is pissing fuel onto the exhaust header!
Damn premium fuel must have cleaned out whatever gunk was sealing up the old O-rings in there!
Oh well, good excuse to renew them - probably should have done that already.
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