I have a 98 f150 with a 4.6L and 5 speed trans 4x4. on cool mornings after start up the eng will bog down when you put it in gear and start to go. then i let off the pedal and the rpms return to normal. then it ok the rest of the day. Has anyone else had this problem? if so what was done to fix it? it has done this sence it was new.

 

Clean or replace the Idle Air Control valve. Do a search here, there are some pics of it.