Intermitent Accellerator Fault?

[Dooffle9]

Hi

Was wondering if anyone could help with this problem.

The inlaws have an Avensis Spirit VVTi 2.0 auto, on a 56 plate, this car was bought from new and has a massive 4k on the clock. :D

The problem is that when the motor is started and placed in drive and throttle applied the engine will not pick up. This also happens at times when not in drive. It happens when the engine is cold or warm. Turning ignition off and on rectifies the prob most times but sometimes needs turning off and on a couple of times. No fault code shows.

So it's been back to Toyota main dealer twice first time, NFF. Second time ECU re-programmed. It is currently at the dealers for the third time, they are still saying they can't find a fault, and have never had this fault before. They also said this could be a result of heavy braking . Mentioned to them that would be a little daft especially if you need to do an emergency stop :D

The car is still at the dealers now, since Friday. They have been informed that the car will not be accepted back until they guarantee the fault is rectified.

It has also been noticed that the economy has dropped.

Any Ideas as to the cause?