I'm annoyed at not being able to sort this out myself, but on the off chance anyone else has come across the same problem and found it to be something bizarre like a faulty electric window switch, I thought I'd ask.

From cold, for the first couple of minutes, my engine idles and runs as sweet as an asian school girl wrapped in candy floss skipping through a meadow. But once it's warmed up a little a f**koff big tentacle monster shows up and utterly destroys her in ways only a cartoon school girl can be... Slight exaggeration, but basically it starts misfiring at idle, usually only on 3 cylinders and sometimes down to 2 (although impressively maintaining a solid 900rpm despite this). Then at part throttle (while stationary and out of gear) it hunts up and down by about 500 revs, switching from higher to lower regularly like clockwork every 2 seconds or so. This translates into very jerky and lumpy driving at low throttle around town, a little little like it's kangarooing but it's not. Once it gets above about 3000rpm it's all nice and sweet again and little Mai Ling goes back to skipping along all merrily and gracefully.

So far I've tried:

New ICV
New MAP
2nd hand (but working) TPS
Lambda
Spark plugs (All looked nice and healthy but I changed them anyway)
The coils don't appear cracked or faulty
Coolant temp sensor
A few extra earth wires from the block/gearbox etc just to rule that out

The regularity of the hunting at idle definitely suggests something electrical, but I'm at a bit of a loss as to what it might be. I've read recently that a moody PAS sensor can cause some strange running issues so I'll try unplugging that next and see how it goes, but other than that, any thoughts?

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Ph1 306 GTi 6 | RX8 231 S1 | YBR 125 Cafe Racer | MT-03 660

I'd definitely recommend unplugging the PAS sensor, been known to cause all sorts of issues.

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"Supercharged - 454.1bhp/317.5lb/ft"
Peugeot 306 GTi-6
2000 (X), Moonstone

i recently had exact same issue on mine, my pas sensor was already unplugged. i replaced just about everything with good known parts with no results. I then cleaned up all of the the earth connections, problem solved. I'm not saying this will be the cure for you but it worked for me so worth a try, i spent a week trying to solve it and kept dismissing a dodgy earth as i only suffered the problem from cold