I'm still sure my problem is the TB if only because if it start up and its messing about then switching off and re starting does the trick and we know the TB does a sweep to reset on ignition on. I am sure this is not a map problem because my engine was fine on this map for 40k mile. If it was my oil pump i would expect it to get worse with a hot engine but in reality its worse when cold ie thick oil.
That said i am open to any ideas
This intresting, i stole it of another forum about the Audi TT.....read the bit about the lambda sensor !!!!!
Hunting problems, where the engine speed rhythmically varies, can be caused by an air leak on the intake manifold side of the throttle body. This includes the various vacuum lines going to various places. Check for leaks. Spraying WD40 onto suspect areas can help diagnosis as it will get sucked in and burnt and cause an engine speed change. Clamping any rubber vacuum hoses can help too as can using a spare rubber hose as a stethoscope and listening for hissing and whistling.
An unstable idle can also be caused by a dirty throttle body. The walls of the body can become built up with dirt and upset the carefully controlled surface profile needed when the throttle is nearly closed, causing a large or sudden variation of open gap area with small angles of throttle butterfly movement. This tends to cause an erratic idle as it upsets the idle control loop.
A faulty (slow but not dead) lambda sensor can produce an unstable idle and also make it difficult to hold the revs constant at 2,000 or 3,000 rpm etc. as it will tend to suddenly change a couple of hundred rpm as the mixture snaps from being rich to lean etc.
There is also an engine RPM speed sensor G28 next to the throttle on the end of the inlet manifold. It has a 3-pin connector with pin 1 next to the flat end with the tab.
Measure between pin 2 and 3 with a multimeter set to resistance. You should get 730 to 1,000 Ohms at 20 deg C. Resistance increases as temperature increases.
Also measure between pin 1 and 2 and pin 1 and 3 - in both cases it should be open circuit.
If the above isn't obtained replace the sensor.
Coilpacks suffering partial breakdown and a weak spark - and this can last for months before eventual failure - may cause uneven idle, lack of power and jerking acceleration with sudden late turbo (similar to faulty MAF symptoms) as well as occasional intermittent misfire as a clue.