tried this today.
starts cold ok. so I drove 2 miles out and back.
then turned it off as if I was going into a store.

when I restarted it, check engine lite still illuminated. drove it 5mi. returned shut off for about 4mins. tried restart

same deal. fires but stalls. hissing noise heard, try to crank 3 more times before it starts but total amount of time to crank it is about 15 seconds which gives me a "Gen" light.
temp gauge works. reads under 200°.

 

Temp gauge uses a different sensor than the PCM on your truck. (96, right?) So the gauge in the dash may be right, but, need to know what the PCM thinks is going on. Only way to do that is with a scanner. I would be tempted to drive it to the parts store, shut it off, hook up the scanner, and see if you can read coolant temp via the scanner. See what it says.

 

They can see data but getting them to show you is another thing as they say it's a liability (stupid I know)

 

If you have a Android or Windows device( i think others are available also) get one of these...

 

Make sure it connects via credit Bluetooth not WiFi

 

my truck mfg date was a few months before they put obd-II
I don't have digital speedometer and have to read codes with check engine light by counting the flashes.
I just cleaned the sensor/idle air control circled in red on previous posts here. o-ring looked fine so put it back in. gonna try that today. still need a dipstick tube bolt.