Suddenly running rich/lean (not 100% sure) Can someone look at my logs?
 

1995 mk1 eunos roadster japanese import
1.6 short nose turbo
megasquirt pnp2 ecu mapped on 97 unleaded

I had a full day drifting on the 21st no problems, car ran fine all day then a couple of days after, I drove the car for a short drive in the morning with no problems. Left the car for 1.5-2hrs before heading out again and the car would start but cut out again straight after. I found a load of cracks in the exhaust manifold and I assumed it was getting in too much air and throwing the lambda reading off. I had it all welded back up nicely and new gaskets and sure enough it started up and did run better but still not right. I left it to run for a while and opened the idle valve up a lot so it didn't cut out and it seemed to improve by itself. This morning I unplugged the lambda and screwed the idle valve back in so it would idle at 1k revs and it ran almost as normal but still puffing out black smoke on heavy throttle with a more hesitant throttle response as I blipped it.

Compression test shows good-ish figures with around 180psi on cylinders 1-3 and just over 170 on cylinder 4.

Can someone please take a look at my logs and see if theres anything odd? There are 2 in the zipped attachment.

If you want any more info then let me know.

Thanks in advance

This appears to be a dead O2 sensor.