what ecu has it got? and can you definetely confirm the chip being used ?
It shouldn't have lambda conrol unless it's a 4x4 engine or l8 ecu.


One thing not been asked is what is your fuel pressure readings after the reg with vac on and vac off? could be fuel starvation, also what voltage is your fuel pump and ecu supply wires running at with ignition off and on.

as people have said you need to check all the sensors and base map settings etc and get the readings off of them using an multimeter,

it may be easier just to replace for bran new parts, but testing things before would have saved you lots of money and identify the fault rather than 2nd guessing.

I'd advise a specialist to look over the car and get it setup.