I recently removed the exhaust manifold on my '91240. There was moisture in all 4 ports. Not fuel and I don' t think it was coolant. It didn't smell of anything.
I pulled the plugs and they had grey electrodes but that was surrounded by a rust coloured deposit. I've recently ran 98 octane through it.
The valve stems seemed have a sludge build up. Is that OK, normal.
The motor has never been apart since I've had it.
It was only recently (4 mths ago) re-started after a 2 year covid lay up.
The motor runs great. Did 1 hr and a half motorway trip today. Although when I accelerate from standstill it seems to have a little hesitation. Like it's taking a deep breath before heading off. Pictures attached.
Plugs wire brushed and replaced. Also checked leads.
Cheers