The answer is almost certainly waiting for you in your Omex ECU software, plug in and record a log, then methodically analyse the log from the comfort of your sofa.
As you're running ITBs the tuner would have set the ECU up to run Alpha-N, alpha representing the angle of the throttle butterflys (TPS) and N being engine speed (RPM) to give you a calculated approximation of engine load. You should therefore start by studying your TPS and crank position sensor signals in your log, if you're seeing erroneous signal data check your TPS and trigger wheel security and the condition of the trigger wheel, as well as the crank sensor itself and it's spacing to the trigger wheel.
When studying your log, also look at your ignition angle to confirm the idle timing and that the ignition timing is advancing as per your ignition table. I would also expect you'll be running a wide band lambda sensor, so you'll be able to view your lambda feedback in your log and easily establish if the engine is genuinely running lean? Also look at your injector durations (opening times) in your log to make sure they're moving up and down in line with engine speed and throttle position following your fuel table.
Finally, and if everything checks out as good in your ECU log, the trigger wheel condition/security and crank sensor to trigger wheel spacing are also good, whip the timing belt cover off and check your belt tension, then check your valve timing to make sure the belt hasn't jumped a few teeth, the Zetec is not an interference engine.
Fault finding is all about methodical diagnostics, don't just guess the issue is fuel starvation, let the data reveal the true fault, and the good news is our Omex ECU makes this easy.
Good luck with it
Dave.
