I have bad surging as well at some points when part throttle and sometimes I'd get a flashing CEL after a run or two but no codes appears and it goes after restarting the car!
I'm aware that leaded fuel will kill cats which I dont have and screw o2 sensors quick. But is there anything else leaded fuel would do other than these?
Check for black dust around the pulley or through a boost gauge if the boost stop building up when it should at high rpm that's when you got slippage I think.
Put an rst clutch and it'll hold up fine, mine is still going strong at 18k miles with the Whipple with countless street and strip runs. I've seen so many mt82s break with the rxt as well as spec clutches.