Misfire at idle on warm engine

Good evening all

I have a Ford Scorpio Cosworth V6 (BOA) running EEC-IV OBD I & EDIS-6 (wasted spark) which has a rough idle when warm, fluctuating between 750 and 850 rpm with definite random misfires through both tailpipes. Engine has 2 lambda sensors, one on each tailpipe, both were replaced with new universal ones. Also replaced were new platinum plugs & HT leads.

I'm getting codes 136 (HEGO sensor(left) mixture lean & 172 (HEGO sensor(right) too lean. I had 4 other used coilpacks to hand, condition unknown, each one seems to give the same codes and behaviour. I have also replaced inlet manifold gaskets and sprayed carb cleaner around the plenum etc. to check for vacuum leaks.

Fuel pressure is spot on at idle, no drop on open or snap throttle. However the pickup appears to be a little sluggish.

No noticeable misfire in open loop, only closed loop.

MAF has been cleaned and visually looks fine.

I applied a test probe to one of the HT leads, waveform screenshot attached, because I'm leaning towards leaking/blocked injectors causing a big fight between the lambda sensors and the injector duty cycles. So I'm wondering if anybody with more experience than me can spot a smoking gun.

Cheers guys.

Think I found it, or at least found a problem.

Tested each injector individually with a neat little tool which pulses an earth for a fixed length of time, 1 of the injectors would not close. Few taps with a hammer rectified this.

Will give the rails & injectors an ultrasonic clean, maybe a back flush, then a flow test, then submit another waveform.