Ok - done some work on the car today and think i'm getting somewhere with my problems...
The idle problem, and the power / downchanges issue dont seem to be related - and here's why I think that:
Just had all four wheels off (tyre rotation day
) - and noticed that my front brakes are sticking excessively, to the point where there is zero gap between pad and disc, and the hub is very very very hard to turn by hand!
The problem is admittedly worse on the passenger side - which would explain why my car insists on drifting left if I relieve my hands of the steering for a moment.
This would explain why there is a slight problem with acceleration - but more importantly why the car slows down very sharply when doing downchanges.
As for the idle problem - I've swapped the map sensor out yet again today, which as far as I can tell hasn't changed a damn thing.
Symptoms =
rough idle - only 500rpm or so - judders like a v8 and seems to be "hunting" quite eratically.
Other than that, the car's drunk a wee bit of oil in the last 3 months (2.5k miles) - but not what I'd call exessive.
Fuel consumption is quite high - but then if the brakes are jammed, that's not going to be a big suprise (getting approx 250 miles to tank = 32mpg approx).
To cap it all - having just rotated my tyres, I drove round the block for a bit of a test run, and ran over a bloody screw - which has ripped a lovely hole in one of the two decent tyres I had
:bang: 
The idle problem, and the power / downchanges issue dont seem to be related - and here's why I think that:
Just had all four wheels off (tyre rotation day
The problem is admittedly worse on the passenger side - which would explain why my car insists on drifting left if I relieve my hands of the steering for a moment.
This would explain why there is a slight problem with acceleration - but more importantly why the car slows down very sharply when doing downchanges.
As for the idle problem - I've swapped the map sensor out yet again today, which as far as I can tell hasn't changed a damn thing.
Symptoms =
rough idle - only 500rpm or so - judders like a v8 and seems to be "hunting" quite eratically.
Other than that, the car's drunk a wee bit of oil in the last 3 months (2.5k miles) - but not what I'd call exessive.
Fuel consumption is quite high - but then if the brakes are jammed, that's not going to be a big suprise (getting approx 250 miles to tank = 32mpg approx).
To cap it all - having just rotated my tyres, I drove round the block for a bit of a test run, and ran over a bloody screw - which has ripped a lovely hole in one of the two decent tyres I had