There is no way of saying this without caps lock...
SHE LIVES AND BREATHES AND HUMS LIKE A SEWING MACHINE OPERATED BY FASTIDIOUS BEES!!!!!The utter delight that I have been experiencing since half 5 last night, I cannot over emphasise.
Before I'd got my work suit off I marched through the house, and turned her over, to let her run, to see what the state of play was. Lumpy, but not as lumpy as last night, and as the idle crept down...and down...and down...finally settling at a dead-on indicated 500rpm, the temp rose, up to an indicated 92-3, but never seemed to get much more. And slowly but surely with every minute, the burble and slight judders, the momentary rocking from side to side disappeared, leaving a smooth, vibrationless idle. If I rested my hand on the plenum and I were deaf I wouldn't know the engine was running

Just like she used to be!!!
The sewing-machine smoothness was always my favourite thing about the engine...well, 2nd, after the noise she made over 4000rpm

Now onto the super-critical...just two questions -
There appears to be a faint hiss, literally like someone blowing gentle through a drinking straw, right on/inside the breather bridge. It's got brand new seals, fitted with care and a thin smear of clean oil.
Question 1 - Is this the noise of the air passing through normally, or should I be looking further into this?
There's a 'squeeksqueeksqueeksqueeksqueeksqueek' coming from the front of the engine. It
appears to be coming from inside the cam belt cowling - but I wouldn't put £1 on it, it might just as easily an auxiliary pulley.
Question 2- Is this noise a sign of a cam pulley about to fail?
I think it's safe that we can trace this fault now, to a mis-adjusted throttle body adjuster screw, which neither me nor the old man can imagine how that's happened. It's completely stuffed the idle, the ECUs been frantically trying to correct it, but the butterflies being never allowed to close fully has sent everything 'to cock' as we northern fellows say

as per...

I think a final word of thanks to all who have offered top-notch advice and help. Marks guide, and reference to some dodgy mechanics winding the TB open got me thinking... "
hang onnnn, my father's a dodgy mechanic!! Now what if..."
