Just the other day out of nowhere had a 42 show up on scanmaster and SES light came on while on my way back from a t-mobile store to my apartment. So last night i ohm tested the coil pack with my volt meter on Ohm setting and had gotten 12.46K Ohms on 6/3, 12.45K Ohms on 2/5 & 12.36K Ohms on 4/1. So i knew it wasn't coil pack related, so i just to verify the nuts on the underside that hold the ICM to the ground plate are secure unbolt the 2 nuts and bolt to inspect those. They were still super tight so i put it back on and make sure the nuts and bolt are completely tight on the bracket. Then i made sure the ICM connector was free of any debris, blew some canned air on the ICM pins the connector hooks on and the connector before ensuring the connector was seated well and the bolt was tight holding the connector onto the ICM. Then just to make sure the chips were seated properly in the ECM, gently applied pressure making sure they were seated well. I also took a can of air and blew around the area the chips are just to make sure wasn't debris near any pins. I also unhooked the ECM and blew out the connectors & pins on the ECM just to make sure wasn't any debris there. I plugged the ECM back up and fired her up letting her learn again, not sure what it was out of all i did but no code 42 and she's running very happily. No issues to report as of now ( the mal 23 went away after so many starts).
Maybe something to try, that will cure your mal 42 issues.
At least without replacing anything resolved the code 42 and she was code free prior to that out of nowhere 42 deal, which after i did the above never showed up again which i'm quite glad got cured.