This one appears to have done the rounds.
Symptoms are an occasional dramatic loss of power according to customer.
It has a new coil pack and leads (genuine, thankfully).
The battery was replaced but the original was re-fitted.
A used throttle body has been fitted (they never even cleaned it first!)
I have extensively roadtested it and mostly it is ok although possibly a little down on power.
However sometimes on start up but mostly a warm restart the engine runs on only three or occasionally two cylinders.
No misfire codes, just the throttle body code.
What I feel is happening is it is suffering either from sticky valves or tight tappets, the management sees the misfire and cuts out the offending cylinder's injector, very often a switch off and restart brings all four cylinders online and it drives ok. If this was the case I would expect a misfire code but...
Could it be that the excessive throttle required to idle the engine is being interpreted as a throttle body problem or is it cutting cylinders to prevent engine runaway?
I'm going to try and provoke the problem and then quickly do a compression test.
Some kind soul has also probed the wires to the throttle body and injectors, possibly with a trowel, so I've had to reseal the wires. Don't they know how to backprobe a connector?