I have a 96 f150 with the 5.8L, I have a strange starting problem. If the truck sits for 8 hours or more it always fires right up. But if I take it to the store it doesn't want to start again. It turns over just fine it just won't fire. Help me out guys. Thank you in advance!

 

More than likely a bad ECT sensor.
The one with two wires.

If it had no spark than I would have said PIP sensor or coil.