the veering could be a diff issue. if more power is going to one side of the truck than the other, it will cause it to veer off line.
you might want to have a look at the diff gears, since a loose gear meshing will result in the teeth slipping over each other.very bad. likewise, a too tight a mesh on one diff output compared to the other side will cause unequal power distribtion (left and right).
also, check to see that the axle carrier bearings haven't packed in on you on either side of the truck.
if the bearings have siezed, then more power will want to go to the wheel with less resistance. this would also result in the exagerated veering left when you plant it.

i am assuming that your steering linkages and servo saver a working correctly.