O U R   N I G H T F I R E   M G F:  The ongoing juddering problem

The symptoms:
After some driving in a more sporty style (including some engine braking) it *could* happen that the car doesn't pull in lower revs. The car starts to judder and an occasional misfire can be heard in the exhaust. The problem is very noticable and makes the car almost impossible to drive.
Pressing gentle on the accelerator pedal (like reving up to 1000rpm) makes the revs jumping between 800 and 1200rpm and causes an awfull fuelsmell at the rear of the car. At this moment the Test book reports a stepper motor position way out.
Turning of the engine could solve the problem, but doesn't always do the trick. Resetting the stepper motor (by the well known procedure) solves the problem 9 times out of 10.

Movie (AVI) demonstrating the jumping revs (1.7MB)

Things changed so far:
- Sparkplugs (again with new platinum tipped ones, provided by Mike S: € 36.00 (??))
- Rotorarm (thanks to Dieter who helped us searching in Germany)
- Distributor cap (thanks to Dieter again)
- Ingnition leads (thanks to Dieter, Moto-Concept and at last MG-Rover)
- Oxygen/lambda sensor and loom (together with a 'new' exhaust manifold: € .00)
- Throttle position sensor (from the original plastic TB)

Just ordered and will be fitted soon (after delivery):
- Stepper motor (MG-Rover: €130.00)

If needed next on the list will be:
- Fuel pump (sender unit) and/or Fuel Pressure Regulator
- Injector (1 new, swapping it around for diagnosing)
- ECU/MEMS

Other suggestions:
- May be posted on the Bulletin Board
- May be mailed directly to erik.baekelant@skynet.be