Dunno what vintage your truck is, but on my 2002, the MAP sensor is above and to the right of the fuel filter mount as you're standing looking over the driver's side fender. As far as removing the connector, again on my 2002, the red tab on the connector must be moved from its "lock" position before you'll ever get the connector apart (spent 2 hours figuring this out the first time!) If you have a 2002 and want to practice, the same connector locking arrangement is found on the 7-pin connector on the hitch receiver.
Rusty