For the sake of the cost of the sensor, change that, but if you can take it somewhere with a Pectel monitor, they may well be able to diagnose within a couple of minutes.

Can't see that there'd be interference from any of the other sensors, it's direct to ECU, albeit via those nasty, problem causing multi-plugs.

I know what it's like, I had an intermittent problem with MAP sensor AND ECT sensor at the same time a couple of years back - was a piece of cake to find with the monitor (at least when they intermittently went wrong).

If you can get it on a monitor, even if it does show the ACT sensor as faulty - see what happens when you gently move those dreaded multi-plugs, just to be 100%