87 F150 - won't start after warmed, changed ECT sensor - same code 21

I have a '87 F150 5.0. Recently is has been starting fine but after running a few miles, it will start missing and die. After it dies it won't start up until 3-4 hours later, so I assume something is getting hot but I'm not sure what. I changed the engine temperature coolant sensor but it's still doing the same thing. After changing the sensor, I unhooked the battery to clear the codes and I am still gettting code 21 ECT sensor out of range. Is it possible the new sensor is bad or might it be a problem somewhere else that can create a code 21 related to the coolant temperature sensor.

Thanks,

barrin

the new engine coolant temp sensor could be bad .the module on the side of the distributor will kill it if it is bad. usually the motor won't start until you put a new one on. but yours might be going out and is killing it when the module gets hot.if you put one on be sure to use the dialectric cream on the plate or it will go right back out.last one i put on was $15.00. it takes a special tool to loosen the bolts get one when you get the module.

Thanks for the advice!! I don't think (I hope not) the module is going bad; I changed the second ECT sensor (thinking there was only the one) and it starts right up everytime. Take it to town, turn it off and it starts right up, even after sitting a few days. Easy change, easy to get to. I'd dread having to replace the module, but for now it works as it's supposed to. I guess I'll cross that bridge when I come to it. Thanks for your help!!

you bet. no telling how many times i went to get a new part and put it .just to have the vehicle act the same way. just because a part is new doesn't mean it isn't bad. if i get a bad new one i take it back and usually if they have a different brand i go with it.