V6 1998 TRD, lightly abused for 135k miles. Throwing 0306, had plugs, wires and bunch of other stuff replaced. Ran OK for 300 miles then back to rough running with CEL.
After a while, it goes open loop and runs OK for 10 minutes or so.
Since plugs and wires are new, what's next? ECU? Don't trust the shop that took $1650 to not fix the issue to take another go at it (they took care of other issues, so it wasn't a waste of time)