Closed circuit code 42

[yedge]

Start the car everyday, runs fine.
Car warms up and then goes into closed circuit then throws a code
42....,everyday. After a few moments check engine light goes off. Sometimes it will code at
Low rpms, and after a few seconds
Check engine light goes out.
I assume I am rarely running under ECM control since it codes everyday. Changed coil and ignition
Control still coding. Car runs a little
Rich but does not stumble. Any ideas? Like to run under computer control. Thanks

 

[turbo nasty]

https://www.gnttype.org/maint/malf.html#42