Does anyone know what could be causing idle to rise some 200 rpm - i.e. from the usual 800 to some 1000 - when car is warm? If I leave the car idle it rises itself, but if I push and release the accelerator just a notch, idle is back to normal, then if left to its own devices for some seconds, idle will suddenly and for no reason rise slightly once more.
I remember the throttle body was a real nuisance to align when I had the car chipped. Plugs were replaced to no avail. I'm still running the stock '98 BPV. MAF has never been replaced.
Mileage is normal, idle with a cold engine is fine and rock solid stable.
The only other thing is some slight surging at WOT in 5th. At throttle a little over 3/4, there is a very thin band where boost seems to be getting on and off all the time when engine is coasting a slope and surging is very obvious then but at WOT it is very much less noticeable.
Thanks in advance,
JP Roberts