RX7 FD3S - Ignition breakup or something else??

Gentlemen,

I was doing some tuning and 100-200kph dragy gps runs. On my very first run i ran a 6.65s 100-200kph....and afrs on the top of 4th looked ok if not a little bit rich...thats fine. However, my final run....you can see the afr's shoot very rich with zero change to the tune.

Car in question is an fd rx7 and was running 50/50 wmi. Was it because the fuel got too hot as the runs progressed or an ignition issue?

Thanks in advance. Logs attached.