Hey folks,

I have a '99 AE112R Corolla (Australia) with the standard 7A-FE engine.

I am having some problems with the idling after the engine is warm.

It intermittently fluctuates between 700 and 1100 rpm. It doesn't do it consistently - occasionally a quick press on the accelerator takes care of it and it smooths out to 800 rpm - but then it'll eventually return.

There is also a definite small flat spot right at the start of the throttle. This is noticeable when the car is dead cold - driving with low rpm makes for jerking.

The Check Engine Light doesn't come on, but a DIY fault test is returning code 31, which from what I've been able to find, is Vacuum Sensor (MAP) Signal / Vacuum Sensor or Circuit.

It had a full service earlier in the year - new plugs, leads, fuel and air filters etc.

I cleaned the throttle body (sprayed body and butterfly, used toothbrush and rag to wipe out what little muck was there), IAC valve (removed plug, middle hose from throttle body, filled valve with cleaner, turned it side to side - moves very freely), and the PCV valve (removed and cleaned).

Checked all vacuum hoses visually - can't see any cracking.

HELP!