if problem keeps on persist....mayb u should go n get 2nd opinion.....
shouldnt b fueling prob...coz u oni got prob on low rev....if boost then nth happens??? everythin smooth????
if a/f (exhaust) sensor rosak...check light will on.....even check light din on.....consumption will b quite bad...n its very noticable....
if a/f = air flow sensor....then how come oni low rev jerking??? mayb if ur mech got one...can try n see...
i assume u've checked all the basic stuff like spark plug, plug cables, intercooler piping connections, distributor, coil, throttle body, injector clip????
good luck to u on ur trouble shooting......perhaps n get another ecu n plug in to try.....