ok, yes, you are correct. No map sensor. your first post said 1988 so I was basing my answer on an "88 f150.
Idle air control could be sticking so it won't keep up with the idle demands. Make sure the O2 sensor is reading correctly. There is also a possibility of a spark plug
or coil the may be acting up that will affect you idle cold and the IAC not picking up the idle fast enough to keep it running with a miss. but the miss will go away when the engine warms up. You might also check for a vacuum leak into the system while the engine is cold.