@Link0demons- I like that suggestion about the cam timing being out. I heard of another situation like this but on an EJ22 from memory.
Weird behaviour - full throttle it was fine, idle was poor/low, everything in between with load was jolty.
The issue was the crank had skipped several teeth from alignment with the cam belts which were synchronised with each other.
It’ll be worth the effort of removing the timing belt covers to check the alignment - and an easy fix if it’s out.
It’s a cheap fix too if this is the issue. Typically it won’t show up as an engine code either, but may trigger other ones.
Cheers
Bennie