Do you have adaptation for idle? Should be something like CTP...
I had a similar problem with older LH system. The car would set fuel trim code and only CTP adaptation was out of range. I found vacuum leak at the cracked EGR pipe. The leak was only big enough to cause trouble with CTP adaptation. As throttle was opened, the percentage of the leak was to small compare to the normal air flow to cause partial or full throttle problem.
Your car doesn't have EGRs, but check rubber intakes between MAF and throttle actuators for leaks. Driver side would be a primary concern as it has to be disturbed during oil changes.
Mike