Possible Lockup problem???
Ps. also the car has unlocked at about 75 on highway a few times. You just cruising and it unlocks and after a mile or so locks back up to unlock the converter. Have to hook up some logger
and see whether it's one cylinder (mechanical something
to fix) or all of them at random. Though I had this problem
following converter+headers install and I couldn't see bad
misfires attending the unlock, killing the tables for sure
did make it go away.

