Darren139 about your compressor; it is probably due to worn out motor mounts. When the unit engauges, a large load is put on the engine. If the motor mounts are allowing travel, you can really feel the torque inside the cabin. After replacing mine with units from MN12Performance, I can hardly feel the unit at all now.
Check for excessive shifter movement when revving, motor movement, low oil pan near or touching crossmember on the front side, oil filter touching or nearly touching crossmember, ect.
If you are not aware, the stock units are hydralic factory filled and commonly give way to our torque around 50k.
Hope that helps...