Re: new pickups not right
it sounds like they wired the middle pickup normal and not reverse. So you could be getting an out-of-phase signal when the middle pickup is split. take a look at your switch and tell me if you have three red hotwires running it to it, or if there are two red wires from the pikups and one green.
reversing the middle pickup wont effect the sound of the middle position (3) but may improve the 2 and 4 positions. I am not sure if the switch is suppose to be splitting the pickups in 2 and 4 or if it is simply putting the bridge pickup together with the middle pickup. If the switch has black and white wires from the pickups then they tried to wire it up to do a split pickup in the 2 and 4 positions.
the easiest way to tell anything would be for you to take a picture of the switch and post that.