Sometimes, if I switch from neutral or park to drive, the check engine light will turn on and the D will start flashing. However, the flashing D will go away after next startup and the check engine light just goes away a bit after that. I'm not sure if its the park neutral switch that is at fault or if it is just because I have some other weird electrical issue, since sometimes the "tighten fuel cap" light will come on and go away in a very similar manner, but this is new.
Any tips on what to test to see what I need to replace / check?
154206 miles.

 

Likely contacts are worn and now intermittent contact causing the issue.

Best bet would be to replace.

https://acurazine.com/forums/3g-tl-p...7-code-968913/

There's two links to threads in there to reference as well.

 

Thanks.