Okay folks, I've had idle issues for a while now but about a month ago I thought I had it cracked, major ecu updates and also tested/replaced the following:

Vac pipes all sides of the manifold tested with vac gauge, had odd leak but sorted and now 100% no leaks, including pipework to interior boost gauges and boost control solenoid.

Checked spark plugs condition, decided to replace with new anyway

Checked fuel pipes complete, pressure tested and also fitted fuel non-return hose to keep pressure in system (this also helps test the injectors aren't leaking when not running).

Replaced idle control valve after 3 or 4 cleaning sessions but found in the end it was sticking on every 2 or 3 revolutions. Even with drill used, couldn't get rid of ruff spot. 2nd hand cleaned (low miles) ICV fitted and testing 100% for free rotation. New gasket fitted.

Last month i had almost perfect idle, for a while, then started to notice further starts had the same problem again, idle either high or low and yet fuel pressure was perfect. One thing I had noticed was a leak from the SX fuel pressure reg vac/pressure side (where the nipple is), replaced the nipple and also sealed the adjuster screw at the top (just to be sure), leak almost completely gone so I thought that would be good enough but oh no....

Ran her again today, couldn't tune her for consistent idle , kept chasing my tail for good fuel figures and idle either up or down, very rarely stable. Did vac test on SX reg pipework, no leaks, did vac test on SX reg housing itself and I found fuel coming through...she's leaking! So need new diaphram...so glad I've found it but was at the stage of loosing will to live!!! Replacement from Roger Clark will be on order shortly. It better be the final fix or I'll set light to her!

PS Also, somewhere in that lot, I tested the injectors running by switching each individual injector off one at a time to ensure difference noted and there was, same results in exhaust tone each time.

 

Add to this, I changed the old SX reg I had for a new one about 1.5 years ago, so really pee'd it's leaking and has been for some or all the duration of this issue. I recon it's a problem that's grown, changed from ICV sticking and reg being okay-ish to ICV almost not sticking and FPR getting worse. Anyway, onwards now, I hope.