Is there a way to tell if the ACT sensor needs replaced?
It's for my '88GT so I don't have a check engine light.
I heard that if they go bad, it will go into "limp mode".
This has probably never been replaced so do they go bad after a number of miles?
Ummmm, you can always pull it out, stick it in the fridge for a while, pull it out read the ohms, and apply heat with a hair dryer while reading the ohms. The ohm reading should fluctuate, if not its bad. But, still have the codes read that may not be your problem or you may have more problems.