ey all I'm not brilliant at mechanical fault finding so here is the problem

4age from an ae86 (RWD manifold) just dropped into a ke70 and it is doing something wierd, if we unplug the injectors the engine doesnt change revs much (maybe 50rpm max)
the idle is alright and at correct rpm, the TPS is set correct and there is plenty of fuel as you can smell its over fueling and see it on plugs too
when you goto rev it the timing changes so much that it doesnt want to climb revs fast, gets up to temp like normal and stays there

we suspect the oxy sensor is to blame but we don't to what degree it effects the performance (obviously mixture is effected but to what extent)

please help as I'm starting to get frustrated and run out of ideas

cheers