Engine keeps turning over wont start

i had same problem on my 86 22R toyota pickup i would be driving down the road and it would die and the heater would stop working. it ended up being one of the plug in connecters was barely making contact (By the engine fuses on left side.) i pulled the male terminal out a little more with a pair of plyers and it has been fine ever since. that might be your problem.

Year, make, engine and model of the vehicle please.