If temperature decreases but altitude is maintained (constant pressure) then density increases. But MAP should remain the same since pressure hasn't changed and the throttle valve remains in the same position ¿Right?. % power would be increased, since you would be burning more fuel per stroke, now (more fuel flow).
What would happen with EGT? I don't know. On the one hande, less OAT, less EGT. On the other, more FF, more EGT.