94 ford taurus 3.8 cranks but wont start. intermittent problem. this usually occurs after it has been driven and engine is warm. eventually it will start after a few minutes, hours or days and runs OK

. intermittent problem. this usually occurs after it has been driven and engine is warm. eventually it will start after a few minutes, hours or days and runs OK. the engine has also died while running and then cranks but wont start. the engine was recently replaced for an unrelated reason but this problem did not go away.